disk utility showing less free space compared to mac info pane.

I removed the photo library but I assume Photos is still claiming space on my drive. How to permanently remove this library (already emptied trash). I use time machine; with an external drive to store the backups. could this be the problem? I mean that my mac still maintains a hidden backup of my photo library? I identified this problem when trying to download a sound library to my mac and got the notification there is not enough space. Checking the mac info I did see enough space. But using the disk utility not enough room.