monocote vs. ultracote
I'm not aware of any real difference there.
I prefer Ultracote because of its multi temperature aspects which, to me, make it easier to work with. It also has more of a "painted" appearance than does the rather plastic shine of Monokote.
It is a personal choice, I've seen many award winning Monokote jobs and have friends who swear by it --- I find Ultracote fits my skills better.