system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Why do wizard paintings talk but wizard photos don't?

You can interact with both (like when Moody made people in a photo move), but only the paintings can have a conversation with you? What kind of magic goes on in the actual painting of a person to make their image talk?
gpt
I suspect the paintings don't have the memories of the persons they are of; they are more like eternal actors. 

Photos may be similar to a pensieve. They capture the emotion of the subjects, preserving it in one perfect moment. However, they aren't nearly as powerful of magic as the pensieve, and can't have genuine interactions with the viewer.