Is the main character the same as a developed character?

The short answer is no.

A developed character is a character who is more clearly explained than a character who is simply named. Generally, character development will include information about what the character looks like, what some of their past has been like, how they tend to think about certain situations, and what they feel about things or people. The more developed a character is, the more a reader can relate to him or her,...

The short answer is no.

A developed character is a character who is more clearly explained than a character who is simply named. Generally, character development will include information about what the character looks like, what some of their past has been like, how they tend to think about certain situations, and what they feel about things or people. The more developed a character is, the more a reader can relate to him or her, or if not relate, then at least be able to better understand that character's motivations and reasons for certain actions.

More often than not, the main character of a story is a developed character. It would be difficult to have a main character that wasn't also a developed character. But stories can be full of developed characters that are also not the main character. In The Outsiders, for example, Ponyboy is the main character. He is developed quite thoroughly throughout the story, but so are Johnny and Pony's two older brothers. They are major characters for sure, but they are not the main character.