first, this varies a lot, this was simply what i experienced:
recently attended the birth of a close friend's second baby... due to some hospital overcrowding issues, they didn't give her drugs until she was 8-9cm dilated.
it was like watching The Exorcist. if she looked you in the face you would swear her name was Reagan.
she was screaming, crying, gripping me and her husband, begging for medication or to have it stop, between contractions -while there was still a minute or so between them- she was instead collapsed on the bed quietly crying and begging for drugs and repeating over and over in a quiet voice that she "couldn't do it... please, please make it stop", etc.
back labor + what she later described as a feeling like someone was trying to rip her uterus through her stomach.
then they got drugs in her after deciding she was too far dilated to send to another hospital and things were much quieter. she dozed on and off for a while, then came the feelings to push and shortly after she had had her younger daughter.
her first labor was longer but less intense... really not too bad, she says. this one was very quick and very painful (may be because she went from 3cm to 8/9cm in about 2hrs? entirely labor lasted somewhere between 5 & 7hrs, my memory is blurred on that bit) and now, a couple months later when referring to it she can only stand to talk about it for a sentence or two.
my mother's input and that of the nurses that worked on my friend is that "it's the worst pain you can ever experience".
can't say for myself, after seeing *that* i'm even firmer in my wish not to go through it.
it varies per person from what i assume, though, and apparently by labor as my friend's two were so very different in length and pain... but then, on the first one they gave her drug help almost from the start & i wasn't there, so i couldn't judge from the outside lol.
in truth, it's probably just one of those things you get to find out from doing... that's my guess.