The difference between an invitation and an assignment may be whether refusal is possible.

An invitation you cannot decline without cost is not an invitation. The voluntary evening event, the optional survey from your manager, the request from someone who controls something you need. Calling it a choice while removing the possibility of refusal is worse than simply asking, because it also requires the person to pretend.

If you are asking, make refusal genuinely free and easy, and check whether anyone ever uses it. If you are being asked, it can help to be clear with yourself about which kind it is, so you are at least choosing knowingly.