Coral sting?
 

Will a lobophyllia sting a maze coral or a doughnut coral?

LPS in general pack a pretty good sting.....and some of them have a surprisingly long reach with their sweeper tentacles.....Im not sure which of those corals you listed would win, but something will win..... I wouldnt place them to close together if you value them....

Never place corals close enough to touch (just a good general rule). If you think it can sting, but aren't sure, just assume it will sting.

"Better safe than be wrong with a dead coral"

Don't mean to hijack RCK, but I have been wondering about the same thing. I have a rose and a blue milli right next to each other. The rose seems to be growing twice as fast as the blue. Is there a battle going on between the two?

possible , but one thing is for sure is that corals fight for the room to grow and if to close as doug said something will win and when something wins theres a loser as well which usually dies or doesnt grow. always leave alot of room for corals to grow. when placing them in your tank consider 2 things : how easy are they to frag in case they grow to fast and how big they will get in the long run:)