The virtue of an accepted Hajj that is mentioned in a hadith is general and is applicable to both obligatory and voluntary Hajj
Question

                The Messenger (blessings and peace of Allah be upon him) told us in the hadith: “Whoever performs Hajj and does not commit any obscenity or commit any evil will go back (free of) sin as on the day his mother bore him”; does this apply only to the obligatory Hajj? Or does it apply also to the one who does Hajj after the obligatory Hajj, i.e., a Sunnah Hajj? Will he also go back (free of sin) as his mother bore him? If his Hajj is accepted, will he have no reward except Paradise, or is that only for the obligatory Hajj?
Praise be to Allah.
    There are a number of hadiths that speak 
    of the virtue of Hajj, including the following: 

    1.    
    The hadith narrated by al-Bukhaari 
    (1521) and Muslim (1350) from Abu Hurayrah (may Allah be pleased with him) 
    who said: I heard the Prophet (blessings and peace of Allah be upon him) 
    say: “Whoever performs Hajj and does not commit any obscenity or commit any 
    evil will go back (free of) sin as on the day his mother bore him” 

    2.    
    Al-Bukhaari (1773) and 
    Muslim (1349) narrated from Abu Hurayrah (may Allah be pleased with him) 
    that the Messenger of Allah (blessings and peace of Allah be upon him) said: 
    “…an accepted Hajj brings no reward but Paradise.” 

    3.    
    At-Tirmidhi (738) and 
    an-Nasaa’i (2631) narrated that ‘Abdullah ibn Mas‘ood said: The Messenger of 
    Allah (blessings and peace of Allah be upon him) said: 
    “Make the Hajj and ‘Umrah follow 
    each other closely, for they remove poverty and sins as the bellows removes 
    the dross of iron, gold and silver, and an accepted Hajj brings no less a 
    reward than Paradise.” Classed as hasan by Shaykh al-Albaani in 
    Saheeh Sunan at-Tirmidhi 

    The virtue mentioned in the hadiths quoted 
    above includes both the obligatory Hajj and the naafil (supererogatory) 
    Hajj, because of the general meaning of the wording. 

    As the scholars (may Allah have mercy on 
    them) said, the accepted Hajj is that which is not mixed with sin. 

    Shaykh Ibn Baaz (may Allah have mercy on 
    him) said: The accepted Hajj is that in which a person does not commit any 
    acts of disobedience towards Allah, as is indicated by the words of the 
    Prophet (blessings and peace of Allah be upon him) in the report narrated 
    from him by Abu Hurayrah: “Whoever performs Hajj and does not commit any 
    obscenity or commit any evil will go back (free of) sin as on the day his 
    mother bore him” 

    End quote from Majmoo‘ Fatawa Ibn Baaz 
    (16/334) 

    And Allah knows best.