The terms are still used, as others mentioned, because some states still have an AWB in place. The manufacturer may have 2 different product lines, one pre-ban, and one post-ban in order to sell to those folks in states still with an AWB.
Also, many of the firearms and mags owned before the 1994 ban can be worth more, and at times a good bit more to owners in states with an AWB since they either can not get them at all, or they want the original features without the issues imposed by the AWB. Also, as mentioned, pre-ban, as in pre 1994 AWB high capacity mags can be worth more in ban states, because otherwise they are restricted to 10 rounds if the mag is newer.
Hope this helps.