Are the M50 and M51 engines related?

[E3OAB]

Evening gents,

I'm looking into plonking a big derv in my E30. The M51 fits the bill for power and a little bit of tunability, plus I've driven a 325tds and found it to be quite a good diesel engine for its age.

Presumably swapping one of these in (with regards to mounts/loom/prop etc) would be similar to fitting an M50/M52 engine, and it'd certainly be doable, but I'm wondering if there's any relationship between the petrol and diesel engines other than being fitted to the same cars from the factory?

Thanks in advance,
Adam.