They run the Christmas Parade and holiday fireworks from around Thanksgiving through New Years. It will even snow on Main Street. Besides all of the decorations, there will be carolers on Main Street and cookie decorating at Santa's Round Up where you can get your photo taken with Santa and see real reindeer. You can also see Santa Goofy's in Toontown.
Also, the tree on Main Street in DL is real. The one at WDW is not.
Two things that WDW does not have is the Nigthmare Before Christmas layover at the Haunted Mansion and the holiday layover in It's A Small World, which should be back open at the end of November.
Christmas is even more magical at DL.