It depends on which model you are talking about,because the 13" model and some 15" models have 9400MGT which is a low-end cards and can play new games at low settings(some older titles on medium).
But some 15" models and the 17" models have 9600MGT which is a midrange card and it can play games at medium settings(some older titles on high)
Windows, for some reason suffers worse battery life. Most likely due to missing power management software. One thing you can say about apples is they use very nice batteries at the cost of them being non user replacable, at least without voiding warranties.