[PJ]

The whole thing.
There's a million ways to make a watch move.
Other brands design their own proprietary movements.

Bell&Ross basically went to a supplier and said "hey I need an automatic piece to put in my watch case."
A ~$100-$500 Invicta watch uses pretty much same movement.
So other than the casing, the internals are basically all the same. You're just paying for the look/brand name.

I'll give it to Bell&Ross though. Their marketing and designs must be spot-on to be doing so well.