Appear / look / seem

Hi:

Could someone tell me the difference between those three words? I'm talking about the semantic difference, not structural difference.

I think that with "appear" and "look", something is more obvious; something is apparent, while when we use "seem", we are referring to our personal opinions or feelings about something.

-It appears that someone has forgotten to lock the door.

-It looks like someone has forgotten to lock the door.

-It seems that someone has forgotten to lock the door.

Having said that, I'm not confident about how I should explain the difference among them to someone. I'd like to have your opinions on it, please.

Thank you!