They ARE NOT the same thing.
Whether you can grasp it or not, men do have sex without wanting to impregnate someone.
So procreating IS NOT the driving factor.
You’re lost in space here.
Some idiot professor made a comment, and you fell for it hook line and sinker. WRONG!!!!
If your nads weren’t producing the sex hormones of reproduction you would have NO sexual desire. Trying to pretend that sexual desire is unrelated to biological imperative and the REPRODUCTIVE organs that cause that desire just means you flunked biology.
FAIL
So procreating IS NOT the driving factor.
Procreation is THE fundamental driving factor. You're mixing up the subconscious and instincts with pleasure and desire. Just compare it to eating. People eat fundamentally because they need to survive. The fact that food tastes good is simply a biological, genetic construct to aid in the survival of the species. People eat on the conscious level because food tastes good and it feels good to eat. But the only reason our bodies were designed to like the taste of food was because it was necessary to help us survive. Sex is exactly the same except survival of the individual is replaced by survival of the species.