Delete photos on laptop only.

If your mac is synced with iCloud, then anything you do in the photos app will be done in iCloud. So anything you delete in the photos app will also be deleted in iCloud.

You can prevent this either by first disabling iCloud photos on your mac before deleting. But be aware if you then reconnect iCloud photos it may well delete them on iCloud.

Safer would be to disconnect from iCloud and then delete the whole library (using finder, not photos). Deleteing the library won't have any effect on iCloud, because it is only actions you do inside the photos app that are synced to iCloud. Alternatively moving it to an external hard drive would allow you to keep using the photos app on your mac.

If you do it by deleting the library - yes. If you do it by deleting the photos in side the phtotos app, there is risk those deletions will be done on iCloud when you reconnect. I would hope it wouldn't, but I can't be certain.