Is karma of arms giving depends on the reciever? Consider the following situation

There are two people. One of them is enlightened. Other one is not. If I gave something to them equally without knowing anything about them, Are there any deference on that action?

Until today, I thought it depends only on giver's mind. But recently I heard it depend on the reciever's mind also. Ex: It is greater karma if the arms recieved immediately after end of a samadhi.

If this is true,


Are there any other variables that Karma depend on ? (Other than giver's mind and reciever's mind)
Why did Lord Buddha preach "Karma is the thought" ?


This is not only appiled to arms giving. Ex: Blaming an enlightened one vs non-enlightened one.

Kind regards.
Yes the people involved in the donation matters. The only thing which does not matter for karma is the thing given,  but the receiver may not use the gift if it is useless.
This is because matter, physical objects are meaningless in buddhism. This has far reaching consequences, such as why you cannot get into rigth samadhi by focusing on objects, contrary to what other religious people claim. For instance hindus say that mantras can get them into samadhi but that's not possible, because sounds are meaningless. Same thing with the bath that some people take to wash ''the bad deeds'' they did. Physical objectscannot modify your Concentration and karma, only improving your behavior can work on karma and concentration.

So for giving the usual sutta is this


  "I tell you, Vaccha, even if a person throws the rinsings of a bowl or
  a cup into a village pool or pond, thinking, 'May whatever animals
  live here feed on this,' that would be a source of merit, to say
  nothing of what is given to human beings. But I do say that what is
  given to a virtuous person is of great fruit, and not so much what is
  given to an unvirtuous person. And the virtuous person has abandoned
  five factors and is endowed with five.


https://www.accesstoinsight.org/tipitaka/an/an03/an03.057.than.html


  "And how is a donation endowed with six factors? There is the case
  where there are the three factors of the donor, the three factors of
  the recipients.
  
  "And which are the three factors of the donor? There is the case where
  the donor, before giving, is glad; while giving, his/her mind is
  bright &amp; clear; and after giving is gratified. These are the three
  factors of the donor.
  
  "And which are the three factors of the recipients? There is the case
  where the recipients are free of passion or are practicing for the
  subduing of passion; free of aversion or practicing for the subduing
  of aversion; and free of delusion or practicing for the subduing of
  delusion. These are the three factors of the recipients.
  
  "Such are the three factors of the donor, the three factors of the
  recipients. And this is how a donation is endowed with six factors.


https://www.accesstoinsight.org/tipitaka/an/an06/an06.037.than.html