How do I fix this storage issue?

I have 7.3 GB of my storage used by photos/videos but I'm not quite sure how. All of my photos on my Mac are synced on the iPhone but my camera roll is only under 200 images. Here is my concern: if I delete all the synced images on my phone, will it delete them from my Mac? All this syncing really confuses me. What is the best option? I know I'm doing something terribly wrong. I have plenty of space in icloud too. Help!