Creating iPhoto albums that do NOT sync with iCloud

Laser.Pony wrote:

How do I create a second library on an iMac? Is this obvious/easy in Photos?

Close Photos, option-click on the Photos icon. It brings up a dialog that lists all your libraries that Photos can find, and it has a button to create a new library. You can name it as you like.

It's not necessary, but many of us use the app  PowerPhotos ($30) to aid in copying pictures and albums between libraries.

Many of us have more than one Library. It's my Favorites library that syncs with iCloud. Other libraries include more pictures, but I copy the best ones to the favorites library.

Only one library on a computer can be designated as the System Library and connected to iCloud.

Syncing to iCloud is all or nothing. Any photo in an album is already in iCloud.