After the new release of photos, iphoto will be discontinued. I didn’t even bother rather realized about this upgrade till one day. I wanted to reduce space in my mac, iphoto library as well as photos library was taking large space.
When I did find command, both are having duplicate content. But after some Google search, found this article, which clearly explains that files are not duplicate.
https://support.apple.com/en-us/HT204476
Apple achieved this using hardlinking both files. You can verify this with the following command.
ls -i <image file/video file with path>
Take any image file which is duplicated in both directory and execute the above command. The inode will be same for both files.
You can find difference between hard link vs symlink