The B1 remained a wood core ski for much of its run, smooth and maneuverable, but by comparison with today's carver shapes, did not initiate as quickly, or iron out chop or heavy snow as effortlessly. Very nice in bumps, surprisingly good grip on ice if you stayed with them. The woodies were red and white. I actually owned a pair up until two years ago. I think it went to an intermediate style foam core after that, lost most of its guts, and mojo. Cannot recall the color.
The B2 was blue and white, foam core all the way, very versatile all around ski, light, easy to handle, again, very nice in bumps, silky smooth, excellent soft snow cruiser, not especially fast edge to edge, just OK on ice. Lower performance envelope than the B1, but way more versatile. Was probably the world's most popular all mountain ski for its day. By today's standards, not so much of a big deal.
Don't agree that all 14 year olds have to have twins, would depend on whether he already is interested in the park. OTOH, these days there are a lot better choices out there than either the B2 or B1, unless you can get a phenomenal deal and the ski is virtually new. Realize that they represent an older design, long and not particularly high performance for the effort, by today's standards. I'd think instead about a clean used Blizzard 7.6 Magnum, or an Elan 78, or a Rossignol 82 CA Avenger. They'll grow with him. If he wants a good twin, get him a K2 Extreme in 172. Last season's still around new at great prices, excellent all mountain ski.