Your little magic shard thing from the first game is gone, you now get a spell that covers covers and area, preventing or limiting enemy movement. Charging the spell give it a damage effect at the end of the duration.
You now have a mana system, charged attacks, charged specials and charged magic use the mana. You can get some regen from unlocks, from boons that give you mana regen in various forms, or enemies can drop mana to replenish you. It actually feels pretty nice to use once you get used to the change.
It looks like there are more areas than the first, spread between 2 different routes (one of which unlocks later I presume).
There are some new gods/characters with different power ups and a lot of returning faces with familiar power ups. I feel like I've been able to find more of them a lot earlier than the first, with the duo boons also being available right away.
Weapons wise I've unlocked 4/5 so far, all feel and play very differently, whilst also being a bit different from the first game. No aspects yet, but it looks like those are coming along with an additional weapon in a later update.
The mirror that gives you the permanent increases is gone, it is now replaced with a card system. You unlock these with a resource gathered from runs, they each have a power number associated with them 1-6, and your character has an upgradeable power limit of what they can equip (I think the base was 15, I'm currently at 22).
It's more of a resource hunt than the first game, but doesn't actually feel bad at all so far. You now unlock a few different types of gather tools (gathering seeds, fishing, mining ore), but can only have one equipped at any give time. These all go towards unlocking weapons or new things in the shop. I still feel like I've unlocked way more than I did in the early hours than the first game.