What is the difference between Boehm and Albert system clarinets?

Buffet Crampon's Boehm-system E13 and Prodige clarinets carry 17 keys and 6 rings, written 17/6 in its specifications. The Albert or simple system, developed by Eugène Albert of Brussels, keeps more tone holes covered by the fingers. Players value its unkeyed holes for slurs, and the finger-covered holes let them slide pitch, as heard in early jazz bends and smears.