AA vs BB what's the diff?

[bmonroe 4]

both of mine have a .4 nozzle so, what's the differences?

 

[ahoeben 1,986]

Mostly the internal geometry of the path of the molten filament. So nothing you can see with the naked eye, other than the AA vs BB markings.

[tinkergnome 927]

53 minutes ago, ahoeben said:

Mostly the internal geometry of the path of the molten filament.

 

in addition: all parts of the print cores are documented (if you want to dig deeper...):

https://github.com/Ultimaker/Ultimaker3#ultimaker-3