have you taken a look at the help and the kb?
what problems are you running into that you're concerned about this?
the reason i ask is that functionality wise, they are similar, they bond components together and generally won't have any effect on the results. when you're concerned about the results for particular appliccations, that is when you should be interested in this. BUT, have an application to speak to vs generalities is much more efficient.
compatible the nodes are bonded directly, incompatible there is a rigid beam between them, so in the latter, it could be showing stifnesses that don't exist physically.
node based vs surface based, i'm not exactly sure what you're asking about but i think it is the same as above.