What’s The Biggest Difference between Men and Women? Are our bodies that different? The penis and the vagina are more alike than you think. Today we’re giving you the run down on boy parts VS girl parts – stuff the tennis coach left out of your high school sex ed class! All perfectly made with similar functions. Before we get started on birth education in pregnancy, you need to know how powerfully cool your body is and how it can actually let a baby’s head out of a seemingly tiny hole!