Use when someone literally occupies a space where another person was.

Physical Replacement

Often temporary, like covering for someone briefly in a meeting or a seating arrangement.

Temporary Context

Implies doing the duties of someone else, usually due to their absence.

Use when someone has to step in unexpectedly, due to unforeseen circumstances.

Entering a new role with specific responsibilities, more permanent than a temporary substitute.

Emphasizes the legitimacy or deservedness of assuming a new role or position.

Can indicate the start of a routine activity, like beginning a work shift.

Suggests integrating into a pre-arranged or formal setup, like a team or classroom.