Apple offers My Photo Stream AND iCloud Photos its
With My Photo Stream, you can access the recent photos you take with your iPhone, iPad or iPod touch on your Mac and PC as long as you have iCloud installed on all your devices. Photos (except Live Photos) are uploaded to the cloud and stored for 30 days.
To save or back up your photos, you must save them from My Photo Stream to your iOS or Mac device. To see your photos in My Photo Stream, go to Photos> Albums> My Photo Stream (see photo below).
(Note that if you recently created Apple ID, My Photo Stream may not be available. If My Photo Stream is not available, use iCloud Photos to keep your photos and videos in iCloud.)
Speaking of iCloud Photos, it saves all the photos and videos you take and keeps them updated on all your devices. Any changes you make are automatically updated everywhere. iCloud Photos lets you share photos and videos. For example, you can create a shared album and invite friends and family to add photos and video clips.
To enable iCloud images on a Mac, go to System Preferences> iCloud. Click Options next to Pictures, and then select iCloud Photos. (See image above.)
Unlike My Photo Stream, you need an iCloud storage plan to use iCloud Photos. You get a lousy 5 GB for free (really, Apple?). You can choose from a total of 50 GB, 200 GB or 2 TB for $ 0.99, $ 2.99 and $ 9.99 respectively. You can even share 200 GB and 2 TB plans with the family.
To upgrade your storage plan on a Mac:
- Select Apple menu> System Preferences, and then click iCloud.
- Click Manage in the lower right corner.  Click Change storage plan or Buy more storage.
- Select a plan.
- Click Next and enter your Apple ID password.
When you turn on iCloud Photo Library on your device, you can add photos that you add to My Photo Stream from other devices appear in the All Photos tab of the Photos app and are organized for moments, collections, and years. iCloud Photo Library automatically syncs your photos and videos, while My Photo Stream does not.
On a Mac or PC, your photos are downloaded and stored in full resolution with My Photo Stream. On iOS devices and Apple TV, they are stored in a device-optimized resolution designed to save storage space and enable fast downloads.
iCloud Photos stores full-resolution images on your server and on Apple stuff. It supports popular file formats such as JPEG, RAW, PNG, GIF, HEIF, HEVC, MP4 and TIFF. My Photo Stream supports JPEG, PNG, TIFF and "most" RAW formats. Note that you cannot sync albums and photos from Mac or PC via iTunes in iCloud Photos, and any existing albums / photos will be removed if you quit the service.
Do you need both services? I like to have both. But if you don't want to pay for iCloud storage, use My Photo Stream.
If you are willing to pay for iCloud storage, use iCloud Photos, make sure it is enabled on all your iOS and macOS Photos apps, and disconnect My Photo Stream. ICloud Photo Library uploads photos and videos, makes them available on all your devices, syncs the changes you make, and syncs your albums on Mac, iPad, iPhones and Apple TV.
To (above) Simplify things, My Photo Stream is great for people who don't take many photos, don't need to regularly access them on all their devices, or use a different cloud service instead of iCloud.
iCloud Photos is for those of us who use iCloud, many photos and want to be able to see all 'em' across our devices.