Buddha’s views on women and how Buddhism views it

My professor said that it is believed in Buddhism that to attain Buddhahood, you need to be a man, so a woman needs to become a man first. Then she added that Buddha on the contrary believed that addition of one woman into the Sangha would make the Sangha last thousand years more. Why this difference and what are the contexts behind them? What is the exact status of gender equality in Bhuddhism?