I've not played Terraria either. But, Terraria hit it big early into AVWW's development and I really groaned because it did a number of things that we were doing, and some things that we were intending to do but ultimately wound up not doing because Terraria was already doing them (and doing them very well).
So! My list of particular things that Terraria did that I consciously avoided doing with AVWW because I didn't want to be too much like that one:
1. Terraria has tons of Minecraft-style crafting... I think. AVWW has crafting also, but it's more like unlocking units in a strategy game tech tree than it is anything like Minecraft/Terraria. In other words, AVWW is all about the acquisition and expenditure of resources in such a way that you choose what the benefit of those resources will be (multiple spells that share limited components, you have to choose what to get like in a strategy game); whereas Terraria and Minecraft both give you pretty large quantities of most materials but most materials have specific real-world-counterpart type crafting purposes to my knowledge. Well, Minecraft does, and my impression was that Terraria was similar.
2. Terraria emphasizes base-building and from-component-parts crafting like Minecraft. In other words, lay a line of bricks here, now you have a short wall. Make it higher, now you have a high wall. Add in cross-walls and you have a house. Come to think of it, I don't know how Terraria handles the cross-walls exactly, but they must since I've seen their buildings in videos. In AVWW, obviously there's none of that lego-style construction. It simply isn't there. The only construction that we have is more like a citybuilder, where you allocate the resources and then poof -- there's your building. AVWW focuses more on the ramifications of the buildings rather than on their construction, is another way to look at it.
3. Terraria has lots of weapons of all sorts, AVWW has magic and particle effects instead. They have lightsabers and grappling hooks, we have summoned meteors and ride the lightning and so on. The general types of skills and tools you use here are really different since they're all magically-oriented.
4. Terrain traversal and lighting your way in AVWW is a lot easier than in Minecraft, and I suspect than in Terraria. Especially after a little while into the game, anyhow. AVWW's effective-explored terrain is comparably larger than Terraria, possibly -- that was my impression, but I'm not sure on that point? But the terrain is explored more easily and there's more of a focus on the combat and on SHMUP-like dodging of enemy projectiles than there is on actually having trouble climbing up a cliff on its own. The cliffs are there, but they're just one obstacle among many.
5. AVWW has missions, as well as the overarching conflict with the overlord and his lieutenants, as well as the whole tier system, continent system, and limited tier orbs, which are where the long-form strategy-style decisions come into play with AVWW. To my knowledge, Terraria doesn't really do anything along those lines, as its focus was really elsewhere.
None of those are a slam on Terraria -- what it did it seemed to do incredibly well, which is part of why I didn't want to also try to do those same things. But those were some of the areas where we consciously tried to not be too much like Terraria.
