no big difference, But the External bearing type crank has the tubular spindle fixed to the right crank arm

the bearings are exposed to stuff coming off the front wheel, mudguards will cut back on that,
get their mudflap down close to the ground...

feel? you will feel modern since it's the latest stuff..

square taper there are more competing brands, some of the better ones, have superior weather sealing..
they have to be chosen in consideration of what crank is chosen.

see all the what length do i get ?questions here , from those that think they are individual decisions..

I like the setup on my square taper BB to be 3rd ring edge over the fixed cup face,

the 3rd ring has ears coming down to almost touch , eliminating the possibility of the chain
getting wrapped around the BB spindle and getting jammed there..