What is the difference between manga and doujinshi

I just call em all manga's

Manga - Original Content
Doujinshi - Fan made (like Infinite Stratos, Gundam, etc.)

Google

This suffices, but Doujinshi is technically anything that is self-published. An original manga is still Doujinshi if the author releases it independently.

It's a bit more complicated to say it that way, but yea.