Yes male hair does grow faster than female hair atleast according to the only study I could find on the subject (J Invest Dermatol, 56:5, pp 362-365, 1971). However the difference was not much, only about 6.5% longer on average (or about 0.75mm per month). Does less than 1mm matter?
So, why does male hair grow faster than female hair?
Well the answer if you did not guess already is.........testosterone. The effects of testosterone is thicker hair which is related to a longer hair length (yep longer hair, not just faster growth!). (European Journal of Dermatology, 14:1, pp28-32, 2004)
The next quest: Do men really do have a longer growing phase (known as anagen) than women.
Sadly there is no answer to this section. While there is no shortage of studies on women, it seems the societal norm is for men to cut their hair. I was so desperate that I even looked specifically for studies on Sikh men because I know quite a few never cut their hair, sadly I found only studies on balding and loss of hair through traction.
Thicker hair = Longer Hair
So it appears that the thicker your hair is, the faster and the longer it will grow. I guess the fine haired girls like myself can be content with the fact that we will tend to have virtually hairless legs........ lol.
I do think that the fact that men leave their hair alone (i.e manipulate it much less) is also a major factor. It does appear though that they have a genetic advantage.