They are the same act. What you're on about is what I posted - is it sex with someone special - in which case you're making love - or is it just a fling, which is just casual sex.
I won't "condemn" people who have sex - some/most of them probably had it because it was special to them. It's still not adviced though and still doesn't make it good. No guilt isn't good it's destructive - feeling "guilty" isn't the way about it! - but they will just have to take the responsibility and consequences of their actions, and in some cases it could be a scar for life - emotionally, mentally - if the relationship ends up not going well. In the end you're the one who has to choose and if you choose to expose yourself to an unneeded risk of getting hurt, then I suppose it's your choice isn't it? I think it's horrible though if two people slept together and for one it was a special thing and for another it was a "bit of fun" - that'd be the worst... and unless you're sure your partner is committed - that's one of the risks. Even if they think they're committed, and believe it and are genuine - it still may not be the case.