That's a good answer to a tough question,
I have just answered a similar one from a guy about knowing when a girl is satisfied during or after making love. He too just said Sex .... and I wonder if those that ask these questions know the difference ?
To me Sex is just the act of having intercourse with someone of the opposite sex, it maybe for mutual relief but it hardly compares with love making.
To put the word LOVE into lovemaking is to give yourself to the other person as they give themselves to you ... you don't necessarily see it but trust me you will feel it....
If you don't... well that was just Sex !!!