Your first example should work.
Boolean basically means true or false.
Be careful though. CheckGroup will see inherited groups and return true.
For example, if admin inherits respected in the ULib UCL chain... admin's would get returned as true also.
If you only want the respected group to have something, then GetUserGroup is your best bet, and for that you would then use the example you showed already "if ply:GetUserGroup() == "respected" then"