Originally Posted by
Hotel Kilo
The 8 & 9 are basically re-engined 737 8/9.
The MAX 7 is different than the 73-7, so treated as a "new" airframe. The MAX 10 is the Uber stretched 73 and is considered a "new" airframe. Thus both the 7&10 require certification.
That's the 2 minute or less explanation. It's a bit more involved than this but that's about all one needs to now without getting really wonky.
Doesn't the Max 10 have some really complex landing gear as well? I can understand that for the 10 beyond the other variants.