Most people think that male orgasm and ejaculation are two parts of the same process. As shown in Chapter 3 of this site, male orgasm and ejaculation are two different things.

When these two things happen at the same time the man has a `normal´ orgasm, and within Devotional Sex this is called a Climax. When a man has a Climax he loses his erotic energy.

Within Devotional Sex the Knight learns the Taoist multi-orgasmic man technique, which enables him to orgasm without ejaculating. This is called a Crest.
  

For a female an orgasm is a Climax or a Crest depending on how she feels after her orgasm.

If she still has sufficient erotic energy to want to continue sexual activity then her orgasm is called a Crest.

If just after her orgasm she loses most of her erotic energy, and thus her desire for more sexual activity, her orgasm is a Climax.

Note that wanting to end sex because of loss of erotic energy after an orgasm is like wanting to stop eating because you feel full. It is the body which is telling the brain what to do, and the brain just responds to the body’s feelings.

Of course there will be many times when a woman loses some but not all of her erotic energy. In this case it is her mind rather than her body which decides what to do next. If she chooses to continue sexual activity then her orgasm would be called a Crest, and if she decides to end sex then it would be a Climax.
  
The reasons for choosing the word Climax are given in Chapter 1 here.

The other new words used in Devotional Sex are presented in Chapter 1 here.