Are hallucinations that you literally can see them in the real world? As if they’re real as another person? Like you can literally see them with your eyes?

Or can they be your brains imagination pretending/imposing something into the real world that you know isn’t real. Like not really seeing them, but your brain imagining they’re there? Like a maladaptive daydream happening in your head but being imagined into the real world subconsciously? A bit like a child’s imaginary friend.