system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] What level of sentience do moving pictures have? Why can some talk and others not?

Also is there a difference between portraits and photographs?
gpt
Portraits take time to create, and because of the care and attention involved, magic infuses with the paint, giving it a semblance of sentience.

Some portraits, however - such as a Hogwarts headmaster portrait that the castle automatically creates, are completely sentient.