They are not comparable in sense!
'climax' is the most exciting moment in any event or situation (climax of a story ,orgasm in sexual intercourse etc...)
'menopause' is the time in the woman's life ,when her period stops and she cant get pregnant.
The word derives from greek Emmenopauses " emminopafsis", emmino means "the monthly" and it is another word for the period. (Pafsis) means to cease or to stop.
It occurs usually between the ages of 45 and 55.