A new region, new storyline and new characters. (And a few old ones...)
A level limit (Pokémon will stop obeying if they are overleveled and you don't have enough badges.)
Full decapitalisation, cause capitals are annoying.
All trainers have maximum AI and 50 IVs instead of 0 for added difficulty.
Pokémon and moves from gens 4, 5 and 6.
Custom level-up movepools. (They're very similar to XY/ORAS though.)
A fakemon. (Yup, just ONE fakemon.)
Some references to different games and anime.
Reusable and custom TMs.
Move tutors can teach moves multible times, in exchange for Shards.
HMs contain more useful moves.
A Hidden Power checker.
Some cursing words, nothing mayor though.
BW repel system.
Running indoors (Obviously)
Some trainer classed music.
Some Pokémon have their hidden abilities available.
The items sold at Pokémarts are based of how many badges you have.
The alpha covers one gym, but does not stop right away!
In the Alpha, the hack is about 10% finished.
Currently, the hack is about 20% finished.