What happens to photos I deleted on Mac if I choose to enable iCloud Photo Library?

Greetings lisabf,

We'd love to assist you with iCloud Photos. This feature automatically keeps every photo and video you take in iCloud, so you can access your library from any of your devices. Therefore, any changes that you make will update across your devices. Here's how:

"What happens when you edit or delete photos

When you edit or delete photos or videos, the changes are reflected across all of your devices.

Edits show up on all of your devices

When you make edits in the Photos app on your iPhone, iPad, or iPod touch or on your Mac, the photo automatically updates across all your devices, including your Apple TV. So when you crop or enhance a photo from your iPhone, you see the changes when you access your library from your Mac. Your original photos and videos are stored in iCloud and you can go back to them at any time, and revert any changes you made.

Photos delete from all of your devices

When you delete photos and videos on one device, they're deleted everywhere that you use iCloud Photos. If you delete something accidentally, you can recovery it in the Recently Deleted folder for 30 days. After that, it's deleted permanently."

We also suggest being mindful of the following details as well:

"Download copies of your photos and videos

When you turn on iCloud Photos, your photos and videos automatically upload to iCloud. They're not duplicated in your iCloud backup, so you should keep backup copies of your library. Use the steps below to download copies of your photos and videos to your Mac or PC. Or you can import your library to your Mac or PC. 

Download your photos and videos from iCloud.com

1. On iCloud.com, click Photos.
2. Select the photos and videos that you want to download. 
3. Click and hold the download button  in the upper-right corner of the window. If you want to download your content as it was originally captured or imported, choose Unmodified Original. For JPEG or H.264 format — including edits, and even if it was orginally in HEIF or HEVC format — choose Most Compatible.
4. Click download.

Download photos and videos from your iPhone, iPad, or iPod touch

1. Open the Photos app, then select one or more photos or videos. 
2. Tap the share button .
3. Tap AirDrop, then select the device that you want to share with. Learn more about using AirDrop

For large numbers of photos, learn how to import your photos instead. 

Download photos and videos from your Mac

1. On your Mac, open the Photos app.
2. Select one or more photos or videos. 
3. Drag the content to your desktop, or Control-click and select Share > AirDrop."

Click here for more info: Set up and use iCloud Photos

We hope this helps.

Take care.