Speaking only about songwriters, content is where the difference lies. Women writers overwhelmingly choose to write about what can loosely be termed love/relationship/female issues. Yes, there are the exceptions that prove the rule, but if you check the subject matter of women writer's songs on your cds you'll find this rule of thumb is true over 90% of the time. Men, on the other hand range over a much wider choice of topics. I'm making no judgement here just observation. There appears to be no female equivilant to Stan Rogers for instance.
Vive la difference!