I have Baked also! It's currently my favorite UD liner.
One noticeable difference is size, the UD glitter is bigger. Though I understand that may not matter to someone who uses these occasionally. I work in a nightclub, so I get to use mine 3-4 times a week.
I also think UD's glitter shows up much better. I don't need to 're-dip' as much. Even then, glitter liners are kinda funny- one swipe will result in either a little or alot of glitter, regardless of brand.
I love both Peacocky and Divine Lime though- UD only has one very green glitter liner, and it can only be bought as a set of 3 at the moment. It's similar to Peacocky, but darker. That's why I went with Divine Lime because I haven't seen any glitter like that in any brand. (Except maybe Ben Nye, but I haven't used that yet.)
So when it gets down to it EnbalmberBabe- it's really preference. Not every needs to use glitter all the time, and MAC's colors haven't been duplicated yet.