The F83 is the M4 Convertible and the heaviest car in its family: S55 engine, M wide body, plus the three-piece folding metal roof with its hydraulics and the reinforcement an open shell needs. Some two hundred kilos separate it from the coupé.
It yields the same parts an F33 does: condensers, door cards, small parts. That is no coincidence, since the two share their interior and air conditioning entirely.
Where they separate is the metal. Flared wings front and rear, M bumpers, the aluminium bonnet and mirrors on two-piece stalks exist on the M4 alone.
One point that confuses people looking for M4 roof parts: only the F82 coupé has a carbon roof. On an F83 that space is taken by the roof stowage, and a coupé roof panel is meaningless there.