If you talk about the nuances of baseball, of which there are countless, most people couldn't tell you much about the differences in pitches let alone how differently they can all be thrown. How you change the angle of your arm, finger position, and delivery like out of the stretch, change the pitch every time.
Many people know what a fastball, change up and curve ball are but, until we got Dickey, didn't know about a knuckler. Then you include the many different sliders, cut fastballs, two vs four seamers, and you almost never see screwballs anymore. Then you get the different curveballs and the slurve. Until you've watched a guy like Henke throw a forkball you can't really know what it is.
And that's the most basic facet of the game aside from hitting. It's extremely complicated.