the basic idea (as i understand it, but it’s been a while) is as follows. “pleasure friends” are friends that you only do certain (fun) things with, and the friendship is likely to die once either of you stop doing those things. for example, a friend that you only play video games with, or only go to bars with, etc. if you lose interest in a game, the friendship may be over, and it’s usually not a big deal when it happens.

“utility friends” are similar, but instead of doing fun stuff together, it’s more about doing useful things. maybe an example could be friends that you only really study with. they’re probably pleasant to be around, but the main reason you spend time together is that they make studying easier (and hopefully it’s mutually beneficial, but it doesn’t have to be).

the last and hitherto unmentioned group of friends are the “real friendships” or something like that. these are the people that you care about on a deeper level, and who play more prominent roles in many different areas of your life, or something.