not really they wll both make sense, 128 is for relaxed driving, smooth big powerful straight six, it is by no means a hooligan, unlike a 120 CSi, the demographic appeal for both is very different whereas the average 128 buyer will be a newcomer to BMW looking for a "good" price, adequate engine, and the usual BMW stuff in hope of upgrading to a 3 in some years, the average 120CSi buyer will bea boy racer in his mid twenties looking to drive like an idiot and tune the hell out of his car
i do not condone this behavior but it serves a purpose far different than a 128