There are a TON of changes between versions so here's the list

-Made the game run in widescreen

-Remade every. single. map to fit in widescreen and look a little better, along with expanding some of the smaller ones

-Rewrote most of the dialogue

-Edited some of the boss fights

-Made Steve not look like he's on something along with adding some dialogue after his fight

-Remade/regenerated most of the enemy sprites (a few were fine but were missing side view battlers and some were remade entirely)

-Rewrote the final 2 bosses (you actually need to be prepared before the final one)

-Removed the Undertale battle system (though that was removed in an update to the original)

-Fixed the invincible enemy glitch

-Added the subclass system from DS2

-Added a ton of new abilities (mostly from DS2)

-Added more shops to the game

-Balanced the entire game

-Threw out the Blank sprites that were made in MS Paint (though I admit the new sprites are cursed)

-Changed the music for some locations (I mostly kept the music the same but some maps have different tracks that play)

-Made a new title screen (Based off DS2's title)