Yes, quite a bit.

Dragon Bones added 2 new dungeons, housing storage, and the outfit system.

Summerset added a new zone, a new trial, and jewelry crafting. Battlegrounds became base game, Morrowind (zone) is a DLC, and Warden class in a separate upgrade. It also added daily login rewards.

Wolfhunter - another 2 dungeons

Murkmire - added a new zone, a new 4 man arena. Cyrodiil now has destructible bridges and mile gates, and a few extra outposts. It also had some major balance changes. Passive dodge was replace with AOE damage reduction, sorc and light armor damage shields are now capped at 50% of max health, and most sources of Major Expedition had their duration shortened.

You shouldn't ask the sour forums if you should come back. Just log into the game and enjoy yourself.