Oh okay gotcha. Does that go with text messages as well? I was hoping to keep my iPhone and iPad separate with certain apps/settings/phots.
In Settings > Messages > Send & Receive you can change enable/disable what address the Messages app will recieve, and the address it will send from. You’re probably going to stick with the iPhone’s phone number for the iPhone, but you can use any email address you’ve set up on the iPad for it’s Message address.
Also, on the iPhone under Settings > Messages > Text Message Forwarding, make sure you do not have the iPad selected. Otherwise all messages from the iPhone will show up on the iPad. This will, however, prevent you from sending SMS messages. In other words, you won’t be able to send messages to non-Apple devices.
Other message apps will have their own settings. You’ll probably have to create separate accounts for each device. I’m not familiar with most of them.
Photo apps sometimes use the Photo library directly. Others have their own photo library, but can access the main Photo library to import or export photos.
You’ll want to visit Settings > iTunes & App Stores to make sure the various Automatic Download buttons are off; otherwise new perchases will be downloaded to both devices (if they have the same iTunes/App Store account). You can still manually download apps purchased on one to the other without paying twice.