Sigmund Freud touted two kinds of orgasms in women, clitoral and vaginal. More recently, other pundits have added a third kind to the list, the G-spot orgasm. It might appear that women can have three different kinds of orgasms, while men must get by with only one. Actually, male or female, there's only one kind of orgasm, but orgasms can feel different depending on the circumstances and what triggers them.
In both men and women, orgasm involves contractions of the pelvic floor muscles that run between the legs forming a figure-eight around the genitals and anus. With sufficient erotic arousal, these muscles suddenly experience a series of rapid, wavelike contractions, usually four to ten contractions separated by less than a second. One full set of contractions equals one orgasm. In addition, most orgasms include involuntary movement of the hips, chest, head, and/or limbs.
In women, the muscle contractions of orgasms are usually, but not always, visible as contractions of the anal sphincter and the vaginal opening. In some women, orgasm also releases fluid (female ejaculation), from the glands the surround the urethra (paraurethral glands, e.g. Skene's glands). Most women who ejaculate release a teaspoon or less, but some release considerably more. This fluid is not urine. It's more like men's prostatic fluid. Most women can have only one orgasm per interlude, but some (it's not exactly clear how many but a small minority) can have two or more in rapid succession (multiple orgasm).
In men, orgasm typically includes ejaculation of semen. However, different nerves control orgasm and ejaculation. It's possible to have an orgasm without ejaculating (dry ejaculation), usually the result of spinal cord injury or prostate surgery. It's also possible for men to ejaculate without experiencing orgasm (numb come), often because of alcohol intoxication or feeling turned off by the woman or the sex. I've never seen any credible reports of men having multiple orgasms as some women do, but men in their teens and twenties can often raise new erections shortly after orgasm and come again in less than an hour. However, as men age, the time between orgasm and the possibility of a new erection (refractory period) grows longer and may take many hours.
All orgasms result from serial contractions of the pelvic floor muscles. Physiologically, all orgasms are the same. Then why the distinctions among the clitoral, vaginal, and G-spot varieties?
I respect much of what Freud had to say, but when it comes to sexuality, ol' Siggy was sadly misinformed. In his view, clitoral orgasms were the province of emotionally immature women. Mature women had vaginal orgasms. If Freud is right, then only 25 percent of women are mature because only 25 percent of women are reliably orgasmic from intercourse alone. Women's pleasure organ is the clitoris. A great deal of research shows that 75 percent of women need direct clitoral caresses to experience orgasm.
Meanwhile, some--but not all--women enjoy particularly intense orgasms from massage of the tissue two knuckles or so in, on the front vaginal wall (the top if the she's on her back). This is a G-spot orgasm.
But no matter which orgasm a woman has--clitoral, vaginal, or G-spot--physiologically, all orgasms are the same. So why do they feel different?
Consider laughter. Physiologically, it's all the same, but laughs vary from subtle giggles to knee-slapping guffaws. Consider sneezes. Physiologically all the same, but they vary from little snorts to explosions that might take out windows.
All orgasms are the same, but they feel different based on several factors:
Type of stimulation. If the orgasm was triggered by clitoral caresses, intercourse, G-spot stimulation, or other erotic touch (vibrators, anal, etc.)
Context. Orgasms in exciting, new, just-fell-in-love relationships are usually more earth-moving than the physiologically identical response in old married couples.
Duration of lovemaking. Longer sessions--with lots of touching all over everywhere--typically produce more intense climaxes.
I hope people, both men and women, stop feeling hung up on the "kind" of orgasms they or their lovers experience. Instead of wondering why you or a lover has or doesn't have orgasms one way or another, the important thing is to provide safe, gentle, loving, nurturing caresses that allow both partners to relax deeply and become aroused enough to come--however it happens.