Man, communication is hard.
You can say something and someone else interprets it, and they make all the noises to suggest that they understand what you said, but it's very difficult to be certain that you're both thinking the same thing. All too often the same words mean something very different to people.
People also use words more loosely in some contexts and more strictly in others. Like the expressions you mentioned could all basically be synonyms in most contexts, but if you were talking to a sexual partner or a sex therapist, you'd probably want to be more exact with the words you use.
But here's the issue, how do you know how exact someone is being when they're talking to you? If you're guessing at their level of precision, then you're only guessing at their actual meaning. Problematic.