The just means the molds used for the abs caps are either newer or just smoother than the pbt ones. The texture right out of the box is not an indication of plastic material. And once both ABS and PBT shine and lose texture (they both do, pbt just takes a little longer) they’ll feel pretty similar. It’s better to say you just like smooth keycaps more than you do rough ones, rather than saying you like abs more than pbt, as it’s not mutually exclusive. If you’d like I can name the usual texture of several keycap manufacturers.