Question

The terms commensalism and mutualism have the same meaning and are interchangeable.

Answer 1

Nope, they are different
• Mutualism: This can be used to describe an association in which both organisms apparently benefit
• Commensalism: In this association one organism [the commensal] benefits, and the other [the host] is apparently unaffected

Answer 2

@Loser66 is right.

Answer 3

snail and hermit crab-mutualism
i dont remember the name of the fish exactly but small fish and shark - commensalism

Here the small fishes eat the the piecies which fall of when the shark has its prey