I think /u/reessagny has the best description.

okay, once you get past the individuality,, there are some things that seem to be the same across the board.. the first thing is the heat. imagine pouring water that's about the temperature of a really hot shower or bath across your clitoris, and only the clitoris. that first shock of how hot it is. that's about where the temperature of the vagina is once you're inside it. yeah, you could feel the same temperature with your finger, but it isn't the same as with a penis. the cock is much more sensitive. next is the wetness (assuming you've done s good job during foreplay, and no issues interfering). it's slick for sure, but there's this slight drag to it. I think of it like being between honey and syrup. so, if you take a super thick syrup, warm it up to the high 90 s Fahrenheit, then put it on your clit, and rub it in a little (messy and not ideal, but it's the closest I can think of) you'd be right about the sensation of the heat and slipperiness. for a little while anyway. inside the vagina, it gets warmer, and wetter as you thrust (usually). now,, the texture. frankly, it's not that different texture wise than what you can feel with a finger. but the penis is more sensitive, so you feel the friction more. the closest I can compare it is like running just your fingertips over very fine silk. I can't think of any way to roughly duplicate the feeling though. but the thing that really makes it unique compared to any other form of sex is the pressure. once you slide inside, it surrounds you. when you thrust in, there's a slight resistance from the way the vagina seals around you. and when you're pulling out there's this slight suction. but most important is the way it squeezes. even if the last isn't actively squeezing, it's like this hot, wet, tight sleeve just pulsing around you. the closest thing I can think of would be if your partner worked on your clit with just their lips and suction, sort of like giving it a mini bj. it's fucking incredible. and if the lady is adding in contractions, omfg! there's really no way to describe how amazing that part is. but if you insert your finger into your rather tightly formed fist and move it in and out while squeezing, you'll get the basic idea. and when the lady has her orgasm. gods, it's insane. because that squeezing intensifies, but it becomes more like a pulsing thing, usually from the entrance upwards, like this starving mouth that wants to suckle you until every drop is gone. it's! the! best! thing! ever! yes, some are tighter than others. and it certainly changes the sensations. but I can't say that any level of tightness is better or worse. just different, but that may just be me. some guys say they prefer it tighter. myself,, while it's more intense when tighter, there's a level of almost a caress when things are less so. it's nice either way. I can't say I've ever noticed any difference in texture, like ridges or anything. once a woman is aroused and blood is filling the tissues, there's not really any variations in the surface inside. but! labia! you can feel a lot of individuality there. you usually only feel it when sliding in at first, though some ladies have extra full labia minora, and sometimes they'll grip a bit more around the shaft. that can be very nice. very, very nice lol. now, let's say your lady wants to start off without foreplay ( it can be fun, and I've had partners request it occasionally). in that case, you can for sure tell the differences between individuals. some ladies have a bit more surface variation at the entry to the vagina. others are almost perfectly smooth. it's not like a huge difference, but it's detectable. plus, the way the labia minora grip you is rather intense. almost painful if you go too fast. oh! and afterwards! particularly if you're with a partner and aren't using condoms for whatever reason, once you've come and start to shrink. there's this way that the vagina sort of holds onto you. it's like a really long kiss in a way. slight suction, lots of moisture, and this almost tickling ripple as you come out. incredibly unique sensation. comparing things to other forms of sex, nothing beats vagina. it feels like this welcoming, loving home. it's like hugging your lover and knowing that you're home. yay vagina!