Is remastered mainly just less jitter?

Whoa! What? Look who's talking.

Most of you folks are all over the place on this. To the OP's original question: No. As far as remasters it just depends on the purpose of the remaster. Steve Wilson has done a bunch of remasters they sound amazing. The point was to improve the sound. A lot of the remasters from the early 00's were to boost it up and that trashed the DR., The DCC Steve Hoffman Cd's are mostly excellent 

The only other thing I can add of any (potential) value is this. Some remastered discs do a good job of adding additional tracks that are worth listening to. I won't buy a cd any more that isn't remastered, unless it's from Japan, West Germany, or some version that is generally accepted as being one of the best versions.

I agree that remasters are a crap shoot.  But I always seek to hear them as some are worlds better. 

The most recent Beatles is an excellent example - the 24/48 files from their USB key are the best I've heard by a large margin.

I think the 2009/2010 Japanese remasters of the Stones albums are probably the best Stones versions as a group.  YMMV with individual albums.

Any Steven Wilson remaster is an automatic improvement.  So good he has me buying albums I didn't even want before he remastered them.

If you really want a new and compelling way to listen to remastered music, seek out the DVD--Audio, SACD and Blu-Ray multichannel versions.  Some of those are pretty mind-blowing, again starting with the Steven Wilson ones (try King Crimson Discipline on DVDA).

Sorry for going a bit of topic but are there any websites that simply show which is the best lp or cd version to buy for the best recording/sound quality? I was listening to Depeche Mode Violator on CD last night which is easily in my top 10.  Discogs https://www.discogs.com/Depeche-Mode-Violator/master/18080 does a nice job of showing the different versions but is there a website detailing the best sound quality version?  Thanks for the help