I saw my iPad had uploaded all the photos the same as my iPhone. When I delete the picture from my iPad, the picture in my iPhone is also deleted automatically.
Is there any way for me to only delete the iPad photos without affecting my iPhone photos? I want to keep the photos in my iPhone only.
In the future, how can I avoid my iPad automatically uploading my pictures?
What you want to do cannot be done with iCloud Photo Library. By design, all the devices connected to your iCloud Photo Library have a complete copy of your library.
You can turn-off iCloud Photo Library on your iPad and use another app when you want to copy a photo between your iPad and iPhone.
Go to Settings > iCloud > Photos and make sure "iCloud Photo Library" is off.
If you don't want your recent pictures to be copied on each device either, turn "Upload to my Photo Stream" off as well.
On my settings they are both on, but the screencap may help to recognize the correct page:
