Apple is trying to make Photos on all platforms similar enough to give a unified experience across all platforms, but some tools are missing on iOS or iPadOS because of the smaller display size. Some tools are missing in Photos for Mac, because there is no touch screen, and we have use a mouse or the trackpad to perform gestures. When new features are introduced, they are usually first available on the mobile devices (iPhone or iPad) before they are coming to the Mac. It took more than a year, before we could edit the videos the same way on the Mac as on the iPhone, and the straighten tool on the iPhone or iPad as much more versatile than on the Mac. In Photos for Mac we can just straighten the horizon, but not correct the perspective.
The Photos for Mac offers more tools to view and add metadata or to manage the albums. On the Mac we can add keywords to the photos and create smart albums based on several criteria. Smart albums are missing completely in Photos iOS, also keywords and titles. Only very recently, with iOS 15, we can at least aadd captions to the photos and display some information about a photo. We still cannot add custom faces to a photo on iOS.
Memories should be similar on all platforms, because they are syncing with iCloud Photos between our Apple devices, but they are still different on the different system versions. Previously, they have been more versatile on iOS, as we did not really need the customisation tools for Memory movies on a Mac - we could easily create slideshows on a Mac and edit the Memories this way, but now Photos for Mac is catching up, not because there are now more tools to customise memories on a Mac, but because some tools to customise memories have been removed on iOS.