This is a good question. Few people are ever educated about the twin entities of female climax and orgasm. The only kind of 'education' they sometimes get is through pornography and friends who profess to be sex gurus. The former will show you pictures of women convulsing and screaming with pleasure, even squirting ejaculate fluid from the vagina!! The latter will tell you different kinds of tales, depending on their relationship with you, their experiences, their motives, and their own psychosexual biases.
Female orgasm is the subject of entire textbooks and details are outside the purview of a column such as this. However, here are a few basics:
The mere pleasurability of peno-vaginal thrusting is not 'climax'.
A climax occurs when such thrusting (or other stimulus) is continued up to a point where the lady experiences a distinctly higher level of extreme pleasure. This is usually accompanied by physiological changes such as flushing, muscular contractions etc..
Women do not ejaculate during sex. They secrete vaginal fluid. This is a clear transudate that oozes through the vaginal walls. It is not sticky like semen in men.
Prolonged, highly intense intercourse could tire out women too even if they have been passive.
If a woman is in doubt about whether she's attained climax, it usually means that she hasn't !
Lastly, up to 2/3rds of women can attain climax only through clitoral stimulation, and no amount of peno-vaginal thrusting can do it for them.