Both have fully flat beds. Virgin's is slightly larger but you have to stand up to put it in bed mode. BA's on the other hand reclines.
Virgin's seats all have direct aisle access but none have a window view. BA's window seats have up to four windows but you have to step over somebody else's legs or, if seated in the aisle seat, possibly have somebody stepping over your legs.
Virgin's seats face sideways. BA's face either backwards or forwards.
Both have in-seat power and in-flight entertainment. Virgin has AVOD on every flight (I believe) but BA has AVOD on 100% of 747s and 767s and <100% of 777s.
Both have a variable quality of catering and service.