What is the difference between Uncanny X-Men (UXM) and X-Men (XM)?
This is where it gets (even more) complicated. Back in the day there was one X-Men comic book – Uncanny X-Men (actually there’s more to it but for the sake of this question, I’ll leave it at that). The book eventually became so popular that they decided to release another book in 1991, which they called, just plain-and-simple, X-Men (often referred to as Adjectiveless X-Men or X-Men [2nd series]). The books contained two different teams (Blue and Gold), and interacted at varying levels. The X-Men title would eventually go through some name chages, making the whole thing yet more complex (see next question).