Sounds like you've got Photo Stream enabled.
This will make photos you take on your iPhone and iPad available to each device through the internet (iCloud). It's an all or nothing proposition. You can not edit individual photos from the list. iOS 5.1 (rumor alert) is supposed to give this option.
In the mean time, if you don't wan't your iPhone photos showing up on the iPad, go to Settings > iCloud and turn Photo Streaming off. You should also turn it off on the iPhone (same place) and in the iCloud control panel on your computer (if installed).
Unless you decide to use it , of course.
Here is some information on Photo Stream.
iCloud: Photo Stream FAQ