Anything that you read is literature, right? It's actually a bit more complicated than than. For many, the word literature suggests a higher art form; merely putting words on a page doesn't necessarily mean creating literature.
While I believe that literature is not a "higher form" of art than story, it is important to keep in mind the differences between the two. When we discussed this in class, there was a particular definition that really seemed to jump out at me. In short, 'story' is the part that can be made into a film, and 'literature' is the part that cannot.
To further expand upon this, think back to the last book you read. There was probably a part (or many parts) that examined the characters' inner feelings, thoughts, reactions, desires, etc. to some sort of external thing. Now, in a movie of said book, the external thing (whatever it may be) would obviously appear, but what cannot be expressed well in film (the inner thoughts, etc.) would be left out. The external is the story, the internal is the literature.
Now, like I said above, literature is not higher, or better, than story. Sometimes, you don't need to read a literary masterpiece. Regardless, story can, on it's own, be captivating and fun.
Literature and story are equally important in the experience of reading. You will rarely find one without the other, and while it is important to understand the difference, you should still enjoy both.