The Cave of the Ogre Prince

Can anyone tell me what the differences between ogres, trolls and goblins are? I'm going to be ashamed if this isn't a proper ogre.

I've had a little free time recently, so I went into a folder of old files that I never had a chance to finish, and this big guy is the first one I decided to hammer home. Really happy with how he came out. Let me know what you think!