Groups comparison

Class-based - 1981 to 2023
Characters are defined by their class template that dictates what they can do and how they progress.

Multi-classing - 1989 to 2022
Class-based system where player can select multiple classes, though usually limited to 2 or 3. This often limits the development of the primary class.

Class-based equipment (Class restricted equipment) - 1990 to 2023
All or certain (specialist) items, tools and such can't be used at all unless the character is of certain class.

Superclass - 1994 to 2016
Characters have a super-class, a character class that provides the normal level up bonuses and dictates what level you are in terms of everything as well as the maximum profession level and anything else. Or other class that everyone has regardless.

Sub-classing - 1998 to 2019
Class-based system where each class has one or more sub-classes to which the player may or must advance.

Job system - 2002 to 2019
A variant of class system where characters can freely (no limit how many times) swap between classes (jobs), retaining pretty much everything they had in them. Although mostly the currently selected job is actually usable.

Secondary classes(Trade classes) - 2009 to 2014
Includes secondary classes that are practicable outside of primary classes and do not count for multiclassing or sub-classing with primary classes, usually exist in form of crafting/exploration/solo-oriented classes in MMOs.