I put the subject words in single quotes because the point of this topic is to explore both of those things using non normative methods.
i'm a"gay" guy, but this is not a "gay" topic. Even though my perspective is "gay," i hope that doesn't dissuade any and everyone from giving their perspective. As an aside, i was married to a woman for 31 years, so i have a lot of 'hetero' experience.
For me, the focus of sex and my primary turn on is getting inseminated and/or impregnated by a Top. i use the word "Top" just as a general identifier. Some of what that means to me is a person who is (seemingly) wired to want a receptacle for not only His body and what it produces, but also for His emotional disposition, His lust/desire.
For me, a Tops emotional desire is pretty equal to His physical desire, when He 'gets off,' i not only receive into myself the physical expression of His desire and pleasure, but also the emotion, that His pleasure transfers to, and into, me at that point. To me, it's a yin yang dynamic (ideally), the natural attraction and bonding of opposites. i see and feel a Top's desire is to create and control that process, a bottom is a place for Him to exercise and express that.
Here's how 'sex' breaks down for me (these are generalizations):
Penetration: For me, this can run the gamut because penetration starts in the Tops mind/emotions and is an expression of that desire in Him (sorry for the gender specific, but i am attracted to guys lol). It can be the obvious, i.e., His penis, or can be just about anything else He is mentally/emotionally/physically connected to, e.g., any of His body parts, toys, enemas, diapers, humiliation, ad infinitum. By "connected" i mean His desire and pleasure are connected to these as a means of expressing it and "penetrating" a bottom.
Insemination: For me, insemination (simply put) is something from a Top that He wants to leave inside of me beyond penetration as a delivery method (though, to me, penetration can be more than a delivery method). Again, i pretty much always see sex as a combination of physical/emotional/mental, so a Top can inseminate me in all three ways, but the amounts and ways of each of those (i.e., physical/emotional/mental) are a very individual expressions. For instance, for me a Top can inseminate me with semen, urine, feces, a mixture He has chosen for an enema, His joy, His aggression, His anxiety, His pain, His lust. For me, the fulfillment of His desire, His 'orgasm' (in all its many forms) represents a transference from Him into me.
Impregnation: For me, impregnation involves some sort of unification between what a Top has put inside of me and me. Most Tops i have talked to have a sense of this, wanting to 'mark' Their territory. i see it as having all sorts of expression too within the physical/emotional/mental context/s. For instance, some Tops enjoy changing the look of Their bottoms anus, making it look like a "pussy." Or "feminization" where a Top 'impregnates' His bottom on a psychological/emotional level.
The first time i connected consciously with the fact that i was impregnated by a Top was when a Top urinated inside of me. It was a regular FB who was accustomed to breeding me with His semen. He was a subtle Dom who i never saw, but was bred by on a weekly basis. He always wanted me waiting naked and face down on my bed and He's just come in and mount me and cum in. The relationship was one of mutual affection and trust, so He knew what He could do. On one occasion, instead of getting up after cumming, He stayed deep and just relaxed. After a bit, i started to get a warm, full sensation inside and realized He was urinating deep inside of me. At first, i was startled, but He relaxed the weight of HIs body on me further, sort of subduing and assuring me simultaneously while whispering in my ear how good He felt. He knew me and i was immediately receptive and aroused. After, He withdrew and replaced His penis with a butt plug and before leaving said: "lie there like that until I text you." He texted me three hours later and informed me that i had absorbed a lot of His urine and that when i urinated i would know that He had impregnated me because my urine would smell like His. He told me i was now His "piss slut." He was right on both counts. It was a powerful example of how a Top can penetrate, inseminate and impregnate a bottom. It opened a whole new world for me, realizing that there are all sorts of ways to get "pregnant."