Ah, I think you are referring to why some games you win a different number of points than others and how this is calculated. Number varies because you are more likely to win versus certain players and how it is calculated has to do with the rating formula - nothing specifically about the site chess.com.
chess.com uses the glicko rating system if you want to look up that 
It is virtually identical to elo.
I'm not sure if this is the right forum, because it's more of a question about this site than feedback, but where are the points differences set between players that make the points for winning and losing 8/8, 7/9, 6/10, etc?
Like if there are fewer than 50 points between the players, is it 8/8? If there are 51-100 points between them, is it 7/9?
I know I'm not explaining that well, but I hope you know what I mean just out of familiarity with how the site works. Thanks!