From IFWiki

A walkthrough is a list of commands; one that will typically, if entered into a game, produce a winning ending.

Extensive walkthroughs explain why to perform the various actions, and may include a number of optional commands that are not necessary to achieve a winning state, but which are required for the player to understand the plot of the game, to get a higher score than necessary to win, or just to observe the game's more interesting aspects.

Abrupt walkthroughs also exist which only offer the sequence of actions absolutely required to reach a win, or in the case of multilinear games, one of the better endings.