Userlevel and visibility

Hi everyone,

is there a way to make two userlevel not really be able to interact with eachother? E.G. I want to have a userlevel for users below 18 and one userlevel for over the age of 18.

I would like to make it so users over 18 cannot interact with user below 18, as a security feature. Is there a way to manage that?

Thanks in advance!