Oxer - is you horse clipped in the recent picture as well? Also your guy looks to be a brown who sun fadded really bad and/or is now getting a much better diet that is improving his coat quality and color.
Cat - Rascal is just plain silly. Lol I really do think his color difference is
SarahAnn - You guy is also a brown.
Pretty typical for browns to go much darker in the winter.