Storing Photos: iCloud vs external hard drive
Is it better to have all my photos in the cloud or on an external hard drive?
Are the photos on my iMac taking valuable space?
[Re-Titled by Moderator]
iMac 21.5″, macOS 15.1
Question marked as
1 both. Neither alone is sufficient to backup your data. If you’re part of keep your photo library on an external drive, use a second drive for your Time Machine backup
2 yes. Photos on your Mac consume space. If you’re part of sync with iCloud, you can elect to optimize storage on the Mac to make the library smaller. But, you then would back up lower resolution images to Time Machine.
see Move your Photos library to save space on your Mac - Apple Support