Once upon a time, there was a man who visited three different women on three different nights. When he left woman number one, she told the man that had been the best sex she'd ever had. On night two, he left the second woman as she murmured that he'd been the best f**k she'd ever had. And on the third night, the third woman held him tight and whispered how she loved his lovemaking. The dazed man sat back on night number four with a beer and a few friends and wondered how three different women came to three different conclusions when in his mind, he'd done the same thing each time. "Well," asked one of his buddies, "what did you do each time?" He took a deep draw from his beer and looked at his friends mischievously. "What do you think I did? I screwed them!"
See friends, it's all about perspective. What one person sees as love, the other may see it only as the means to an end. Is one better than the other? Who's to say? Can the terms be interchangeable? Sometimes. It depends on the persons involved.
As a writer of erotica, I do focus on these terms and what they might mean to the characters involved. Can the same people be intimate at varied points and be able to call their joining making love at one time, f***ing another time and sex yet another time? Absolutely. Can I have people who get off thinking they're screwing someone? How about a character who is morally offended at the more vulgar term? Of course. Just as people are different, so to are the people I create. My job is to breathe life into characters who are varied and will have different thoughts or beliefs. If I do it right, they will eventually achieve balanced and mutual viewpoints so nobody ends up being the butt of a piss-poor joke like the one at the beginning.