The struggle and change of your protaganist is what makes a story a story. Many writers get caught up in giving their readers details of crisis when the true draw of a story, the thing we as readers want to know, is the metamorphosis of the character.
The difference is that crisis is usually a circumstantial event or action, such as a car accident, a robbery, a break-up in a relationship. Conflict is the choices or struggles the character has to make, sometimes because of crisis. Conflict happens inside the character. Dennis Jerz, Associate Professor of English at Seton Hill University does an excellent job of defining and simplifying conflict versus crisis on his weblog.
The two biggest mistakes new authors make are weaving in too many conflicts or focusing too much on crisis. Well-written novels strike a balance of crisis and conflict. The perfect balance will evoke empathy for your characters from your reader.
When an author truly encompasses good conflict, the reader is left thinking about the story for days after putting down the book; left wondering what would happen next.
Other struggles may be found in your character versus nature or your character versus God or religion.
Different genres can focus on different types of conflict or incorporate several. It makes sense to realize that romance is going to have Relational Conflict and a thriller is going to be Situational.
Conflict can also be described as internal and external. However you want to think of conflict, the struggle and growth are the main infrastructure of fiction. Without conflict, there is no story. Conflict is the suspense and the excitement that makes your story move from the beginning to the climax, the turning point. The resolution.
Simply put, the main character in a good story has to evolve, has to struggle, has to make choices to effectively transition or change. They may or may not succeed, depending on your direction and imagination. But if your character isn’t evolving, then your story isn’t going anywhere either.