In my opinion, they are both full of great ideas. There isn't any overlap as far as effects are concerned. There are small similarities with methods here and there.
For the most part, the effects are all different enough that it's hard to compare them. The first volume has a few effects with actual coffee being poured on a plate or napkin. These are super fun tricks, they feel REALLY different but they are also kinda messy. The second volume is a little cleaner and so there's more material that I prefer on the second volume. Liquid magic gets complicated.