When you say they are going to Google Photos, do you mean you can see them in Photos, or that they are being sync'd to your online account?
Google Photos can function as a regular gallery. In this case, photos are not being saved any differently and Photos is simply reading them the same as your stock gallery. This isn't something you can change, other than to stop using Photos to view pictures.
Photos also has a backup and sync function tied to your gmail. This can be turned on and off in the settings menu of the app, as well as when (such as requiring Wi-Fi or charging to sync).