I have been carrying this question around for a lot of time. How exactly does a user's rating change in codeforces? I have read a couple of blogs that analyse the rating system, but I do have a couple of doubts.

The main one which I'd like to address (and possibly get answers to) through this blog is, this: Do rating changes in contest happen based on tags or based on rating?

For example, lets say a user is at 1599(specialist) and another user is at 1601(expert). If both of them have solved the same problems in the same time during a contest, does the rating increase significantly more for the 1599 user because he's a specialist and less significantly for the 1601 user because he's an expert? Or is the difference not significant for both of them because they have a very similar rating?

Thank you!