Blimey Manda - an open invitation for sweeping gender-based generalisations? Really?
The biggest difference created in the early stages of pregnancy when testosterone floods the foetus and initiates gender assignment in the brain. The body follows later and in some cases you get folk in the wrong body. But cultural gender reinforcement/nurture has a huge impact and that is largely predicated on roles defined before the beginning of mankind in a survival context self-selecting the best species survival roles for the individual e.g. most men became hunters in the early days. Reinforce those roles over a few hundred generations and nurture starts to impact on nature as we form the neuron networks most appropriate to our survival in the modern context and pass that evolution on to our offspring.
With all this going on, there is a case for the genders "thinking differently" and having different sensitivities in their emotional consciousness - although obviously that can't be applied across the board as some men are women and vice-versa and every one of us falls somewhere on the spectrum of gender mind/body disparity, Nat for example.
Different sensitivities and role-induced emotional consciousness can therefore leave the door open to propensity towards gender-based distinctions in opinion (e.g. politics) although I don't believe anyone has tried to prove this by isolating groups from their influencing environments e.g. families/location/social status etc.
But broadly speaking, there is a spurious case for the "Men are from Mars, women are from Venus" approach to inter-gender relationships.
And that's also why advertising, literature and so much more in life is gender-targeted.
And most men don't have tits.