Why do women have 2 make up the days missed during ramadan (bcos of menstration) and nt prayers? ?

I've been researching this topic for a while bt cant seem to find the answer..... i'v read and heard tht during menstruation a woman is nt allowed to pray and she doesnt have to make up those prayers.... bt during ramadan if she misses any days of menstruation then she has to make them up..... my question is why???.... whts the reasoning behind this??? is it true???? can anyone provide any proof from the Qu'ran?????? thx in advance for all the help!