hey man, basically there are two different kinds of bases, sintered and extruded. an extruded base is what you find on a lot of cheap skis and park skis because its easy to repair, softer (so you can get a more buttery ski), and requires less maintenance because there are fewer pores in the plastic to absorb wax, so you "dont have to wax it" per some reps. the downside is that because its softer it can be damaged easier and isnt as fast because it doesnt absorb as much wax.
sintered bases are a different plastic, and without getting into specifications, a different process to produce. it is a lot harder, more porous, and therefore more durable and faster, but harder to repair. a lot of companies will list all their bases in their brochures, and the higher-end the sintered base is, the more pores it has for better wax absorbtion. thats really the only diff.
as far as i know.