The different stationary phases as in reversed and normal phase chromatography?

Typical stationary phases for normal-phase chromatography are silica or organic moieties with cyano and amino functional groups.

For reversed phase, alkyl hydrocarbons are the preferred stationary phase; octadecyl (C18) is the most common stationary phase, but octyl (C8) and butyl (C4) are also used in some applications.