They are all different sets. In my opinion 1st chronicle, which you have, are the weakest though still fun. The 3rd chronicle has the most complex (of the current AEG decks). Also 2nd and 3rd come in boxes with no draw string bags.
Here are my brief descriptions of each:
2nd - Vorpal Sword - Cross between Love Letter and Lost Legacy. Several cards have identical counter parts as Love Letter. You will see more elimination here, more similar to Love Letter.
2nd - Whitegold Spire - Games last longer due to reshuffling of cards. Game focuses on points from the cards instead of elimination or finding the Lost Legacy, though finding it does give extra points.
3rd - Sacred Grail - Introduces hidden information and bluffing mechanic. A lot more mind gamey than the other decks.
3rd - Staff of Dragons - Lots of elimination with heavy risk/reward trade-offs.
The 4th Chronicle is out in case you didn't know.
4th - The Wearwolf - A larger focus on the Investigation Phase.
4th - Undying Heart - Some elimination with turn skipping mechanics.