Well, for starters, internal stimuli is when your body reacts based upon something that you feel.
Like, when you describe your hunger, the feelings behind that. Or the churning sensation you get when you're anxious or afraid.
External stimuli is much different. It's when your experience changes outside the body.
Your senses can detect information from outside the body.
Like when our bodies respond to the change in weather, or to some sources of danger.
Well, glad I could help, byee