Virtually every professor wants to see a clear thesis statement, but some insist it must appear in the last sentence of your first paragraph, nowhere else. One might hate subtitles; another might be adamant about the font you use. Some might want loads of outside reading, while others will actively discourage you from going outside the text.
Though it can be frustrating to have to adjust to a different set of expectations with every class, this variability isn't necessarily a bad thing. Learning to write means learning to write for an audience, and the sooner you learn that audiences are heterogeneous, the better you'll be.
Note, though, that grades aren't quite so arbitrary as they sometimes seem. Though it may seem you're getting contradictory advice from two professors, they're probably just different ways of emphasizing broader points. If anything's confusing, don't hesitate to ask your professors to clarify something. It can only help.