The difference between sending salaams on the Prophet (peace and blessings of Allah be upon him) and sending blessings
Question

Is there any difference on offering between blessing's and salaams on the prophet?
Praise be to Allah.It is prescribed for the Muslim to pray for peace for the Prophet (peace and blessings of Allah be upon him) and to send salaams upon him, just as it is prescribed to pray for blessings for him. The evidence that it is prescribed to send salaams upon the Prophet (peace and blessings of Allah be upon him) is the verse in which Allah says (interpretation of the meaning): 
“Allah sends His Salaah (Graces, Honours, Blessings, Mercy) on the Prophet (Muhammad), and also His angels (ask Allah to bless and forgive him). O you who believe! Send your Salaah on (ask Allah to bless) him (Muhammad), and (you should) greet (salute) him with the Islamic way of greeting (salutation, i.e. As‑Salaamu ‘Alaykum)”
[al-Ahzaab 33:56]
It was narrated that ‘Abd-Allah said: the Messenger of Allah (peace and blessings of Allah be upon him) said: “Allah has angels who travel about the earth, conveying to me the salaams of my ummah.” (Saheeh Sunan al-Nasaa’i, 1215; al-Silsilat al-Saheehah, 2853). 
It was narrated that ‘Abd-Allah said: “When we prayed with the Prophet (peace and blessings of Allah be upon him) we used to say, ‘Peace be upon Allah from His slaves and peace be upon So and so.’ The Prophet (peace and blessings of Allah be upon him) said, ‘Do not say “Peace (salaam) be upon Allah”, for Allah Himself is al-Salaam. Rather say, “Al-tahiyyaatu Lillaahi wa’l-salawaatu wa’l-tayyibaat. Al-salaamu ‘alayka ayyuha’l-Nabiyyu wa rahmat Allahi wa barakaatuhu. Al-salaamu ‘alayna wa ‘ala ibaad-illaah il-saaliheen (All compliments, prayers and pure words are due to Allah. Peace be upon you, O Prophet, and the mercy of Allah and His blessings. Peace be on us, and on the righteous slaves of Allah).” If you say this it will be for all the slaves in heaven and between the heavens and the earth. [Then go on to say] “Ash-hadu an laa ilaaha ill-Allah wa ash-hadu anna Muhammadan ‘abduhu wa rasooluhu (I bear witness that there is no god except Allah and I bear witness that Muhammad is His slave and Messenger).” Then choose whichever du’aa’ you like and recite it.’”
(Narrated by al-Bukhaari, 835) 
It was narrated that Faatimah, the daughter of the Messenger of Allah (peace and blessings of Allah be upon him) said: “When the Messenger of Allah (peace and blessings of Allah be upon him) entered the mosque, he would say, ‘Bismillaah wa’l-salaam ‘ala Rasool-illaah. Allahumma ighfir li dhunoobi waftah li abwaab rahmatika (In the name of Allah, and peace be upon the Messenger of Allah. O Allah, forgive me my sins and open to me the gates of Your Mercy).’ And when he exited he would say, Bismillaah wa’l-salaam ‘ala Rasool-illaah. Allahumma ighfir li dhunoobi waftah li abwaab fadlika (In the name of Allah, and peace be upon the Messenger of Allah. O Allah, forgive me my sins and open to me the gates of Your Bounty).’”
(Saheeh Sunan Ibn Maajah, 625) 
It was narrated from Abu Hurayrah that the Messenger of Allah (peace and blessings of Allah be upon him) said: “There is no one who sends salaams upon me, but Allah will restore to me my soul so that I may return his salaams.”
(Saheeh Sunan Abi Dawood, 1795) 
It was narrated from ‘Abd-Allah ibn Abi Talhah from his father that the Messenger of Allah (peace and blessings of Allah be upon him) came one day with evident signs of happiness on his face, and he said: “Jibreel (peace and blessings of Allah be upon him) came to me and said, ‘Would it not please you, O Muhammad, to know that no one among your ummah will send blessings upon you but I will send ten blessings upon him, and no one among your ummah will send salaams upon you but I will send ten salaams upon him.”
(Saheeh Sunan al-Nasaa’i, 1228) 
Sending salaams upon the Prophet (peace and blessings of Allah be upon him) is one of the rights that the Prophet (peace and blessings of Allah be upon him) has over his ummah. The Muslim is commanded to do this either in general word or in the specific phrases narrated in the reports, such as sending salaam on him in the Tashahhud, and when entering or leaving the mosque. The command to send salaams upon him (peace and blessings of Allah be upon him) even in his absence is one of the unique blessings that Allah has bestowed upon him alone, which he does not share with anyone else, for it is not prescribed to send salaams upon any specific person in his absence apart from him (peace and blessings of Allah be upon him). Another of his unique privileges is that the salaams of his ummah are conveyed to him, so a person may attain the virtue of sending salaams upon the Prophet (peace and blessings of Allah be upon him) and it reaching him even if he did not have the opportunity to meet him during his lifetime and even if a person is not able to go to his grave after he died. 
With regard to praying for blessing for the Prophet (peace and blessings of Allah be upon him), this is also prescribed in Islam. One of the reports that prove that it is prescribed is the saheeh report from Abu Mas’ood al_Ansaari who said: “The Messenger of Allah (peace and blessings of Allah be upon him) came to us when we were sitting with Sa’d ibn ‘Ubaadah, and Basheer ibn Sa’d said to him: ‘Allah has commanded us to send blessings upon you, O Messenger of Allah. How should we send blessings upon you?’ The Messenger of Allah (peace and blessings of Allah be upon him) remained silent until we wished that he had not asked him. Then the Messenger of Allah (peace and blessings of Allah be upon him) said: “Say: Allahumma salli ‘ala Muhammad wa ‘ala aali Muhammad kamaa salayta ‘ala aali Ibraaheem. Wa baarik ‘ala Muhammad wa ‘ala aali Muhammad kama baarakta ‘ala aali Ibraaheem fi’l-‘aalameen innaka hameedun majeed (O Allah, send blessings upon Muhammad and upon the family of Muhammad, as You sent blessings upon the family of Ibraaheem, and bless Muhammad and the family of Muhammad, as You blessed the family of Ibraheem among the nations. Verily You are Most Praiseworthy, Full of Glory). And the salaam is as you know.”
(Narrated by Muslim, 405) 
Sending salaams upon the Prophet (peace and blessings of Allah be upon him) may be done by saying “Al-salaamu ‘alayka ayyuha’l-Nabiyyu wa rahmat Allahi wa barakaatuhu (peace be upon you, O Prophet, and the mercy of Allah and His blessings). Or it may take the form of a du’aa’, praying that Allah may keep him sound, such as saying Sall Allahu ‘alayhi wa sallam (may Allah send blessings and peace upon him [i.e., the Prophet (peace and blessings of Allah be upon him)]. A person’s sending salaam upon the Prophet may be done by mentioning Allah’s name al-Salaam by way of seeking the blessing of that name and this name is suited to the context because you are asking Allah to keep him safe and sound, as if one is saying “O Allah, Whose name is al-Salaam, keep your Prophet (peace and blessings of Allah be upon him) safe and sound.” When the word Salaam refers to the name of Allah, it appears with the definite article al-, unlike when the word salaam appears in the context of praying for peace, tranquility and soundness to be bestowed by Allah upon His slaves, in which case it appears without the definite article. “Because salaam from Him means any amount of salaam, and any amount of salaam from Him will be sufficient to make any slave of Allah have no need of salaam from anyone else and no need for any greeting from anyone else; and any salaam from Allah will be sufficient to grant him all of his wishes. So the least salaam from Allah – and nothing can be described as least when it comes from Allah – will bring the greatest blessings and will ward off all causes of misery, and will make life good and will ward off all causes of doom and destruction. Therefore in this context, when speaking of salaam from Allah, there is no need for the definite article.”
See Dabaa’i’ al-Fawaa’id, 2/143 
What is meant by salaam is being free from evil and faults. So the one who sends salaams upon the Prophet is praying for him (peace and blessings of Allah be upon him) in this sense, asking for the Prophet (peace and blessings of Allah be upon him) to be protecte from evil, faults and shortcomings. As for blessings (barakah), what this means is steadfastness and stability. Blessing means growth and increase.
 What is meant by praying for blessing for the Prophet (peace and blessings of Allah be upon him) is asking Allah to bestow good upon him, to make it lasting, to increase and multiply it.
 And Allah knows best.