What is Difference between a coder, a programmer and a developer.

Answer 1

All actually means the same thing, but a developer in certain context would mean differently.
For example, a game programmer/coder would just mean he codes/programme the game parts. While a game developer can also mean that he not only programmed the game parts, the also drew arts for the game, etc.

Answer 2

All mean the same thing essentially,

one who writes codes (in a language) to make programs (final product) and develops it (updates or makes it better).

But mostly people use developer to specify a person who codes with a specific language, like Java developer