1) iphone

2) ipad

3) Set up iCloud for Notes on all your devices - Apple Support states:
“iOS 16, iPadOS 16, or later: Tap Show All, tap Notes, then turn on Sync this [device].
iOS 15, iPadOS 15, or earlier: Turn on Notes.”
this makes no reference to synching for my ios15 devices. is the answer to my inquiry that ios16 is required for synching?
4) Set up and use iCloud Photos - Apple Support states:
”Any changes you make to your collection on one device change on your other devices too.”
the photos on icloud.com, the iphone and ipad are identical. this is what i expect with synching and it works flawlessly in the photo app.
notes on the other hand works separately. i have icloud notes, iphone notes and ipad notes. icloud notes are accessible on icloud.com and either device. device notes are only accessible on the corresponding device.
iphone

ipad

thanks for your assistance.