1 - profile rails (THK and HIWIN).
The rest are a bit of a guess, and the machine construction can play a role in their stiffness.
2a - Round (SBR) rails
2b - V-bearings on hardened v rails
3 - CNCRP skate bearing
4 - V-bearings on steel angle ala Joes
5 - delrin wheels riding on 8020 ala openbuilds