Do iMovie and iPhoto share source files or what?

I want to pair down the photos and videos that I have stored in iPhoto.

However, I do not want to mess up my iMovie projects. I hope to eliminate the iPhoto files but keep the iMovie projects.

Can anybody tell me if iPhoto and iMovie use the same photo and video files? How does the linkage work?

I tried a test and made a IMovie project and then deleted the event in iPhoto and it did not affect my iMovie project. However, when I am in iMovie and click on a photo or video and say "reveal in finder" it shows me that the photo or video is stored in iPhoto Library! This makes me nervious about deleting the iPhoto event file.

I am running OS X Mavericks. I am running iPhoto 9.5 and iMovie 10.0