A:AnswerHi!
The difference between the 2 is going to be that this is designed to be a monitor. What that means is, it will auto-wake and auto-sleep for you as your computer does.
This monitor also has an "overclock" mode that can boost it to 138hz which will be slightly better then the 120hz that the LG is capable of. The difference I don't think is noticeably huge but if you're an intense gamer who plays competitively you might notice it.
From what I researched the burn in protection is pretty close to the same. I've owned an OLED tv for about 5 or 6 years now and burn in really isn't as big of an issue as people think it is as long as you're being relatively careful with not keeping static images on the screen for a super long time.
A:AnswerIt depends on the mount that you have. The normal sized mounts for monitors are too small but there are extension brackets that you can buy for it to work.