Seats are the same. I actually dislike the middle seat in the 764, too much traffic on either side. If you're taller than 5' 10" you may prefer a bulkhead. The problem with bulkhead seats for sleeping though is proximity to the galley, a source of light and noise.
Overall, you will find this seat far more comfortable than economy and IMO well worth the extra cost.
It depends upon whether it is a PMUA or PMCO. PMUA are narrower and very uncomfortable, nothing more than economy seat that lies flat. PMUA 767 seats are 2-2-2 in BF whereas PMCO are 2-1-2. PMUA in 777 are 2-4-2 whereas PMCO are 2-2-2, obviously more space. Further PMUA BF seating has zero storage at the seat, everything must go in the overhead whereas PMCO has shelves and a nook behind the seat.
Just ignore this post entirely, it is completely uninformed.