Difference between Fortresses, Endgames and Pro labs.

Recently I was thinking about trying some labs, not just single machines. What is the difference between Fortresses, Endgames and Pro labs ? And which would you recommend to try first (POO, Xen, Jet, Akerva) ?

Fortress is no different from single machines except it has more flags, difficulty increases in next flag and it tests variety of skills. It’s like mixture of hackthebox challenges put in a story line. Even though I haven’t tried any of Endgames or Pro labs, I would say Fortress is easiest. Because, Endgames has level restriction(requires you to be at least Guru rank) and Pro labs are mostly rated as hard.

Fortress is no different from single machines except it has more flags
Oh, that means I’m going for retired Endgames then.

Endgames has level restriction(requires you to be at least Guru rank)
If you have VIP, you can “play” retired endgames (P.O.O. and Xen), at least I have an
option to download connection pack, hope it will work.

Thanks.