How do you compare and contrast two painting?

Question

I am comparing and contrasting two painting: Venus of Urbino by Titian and Olympia by Edouard Manet

Answer 1

Compare the likenesses. If the style, color, subject matter, etc. is the same or similiar talk about how they're similiar. 
Contrast the differences. If the style, color, subject matter, etc. is different talk about how they're different. 
Like the first answer, art is a matter of interpretation, so you'll have to use your own ideas to illustrate the similiarities and differences. Good luck!

Answer 2

The painting "Olympia" was inspired by the Venus of Urbino, a renaissance painting. But instead of using the "Venus" he used a prostitute as his model.