A high alpha acid percentage (AA%) is primarily what gets them classified as "bittering" hops. Typically (but not always), the double-digit AA% hops will be listed as bittering, sometimes as bittering and/or flavor and/or aroma, depending on (naturally) their flavor and aroma. Some of the high AA hops also have good flavor and/or aroma characteristics (Centennial, for instance), some don't (such as, IMO, Chinook).
The high AA hops are typically used more often for bittering also because if it's bittering you're after, it's more efficient (cheaper) to use high AA hops near the beginning of the boil than to use the same hops for flavor or aroma (since you get less and less bittering from hops used nearer the end of the boil).
Hops with subjectively better flavor and aroma characteristics are more often used for flavor and aroma, regardless of AA... and the lower AA hops are used less often for bittering because you need to use more of them to achieve the same bitterness.
Not to say that hops boiled for 60 minutes (bittering) won't lend any flavor at all; some of them will, some of them won't, but it won't be a lot.