Carol Gold wrote: …Is it possible to sort the library by date?
Instead of two views, Library and Recents, it's been simplified into one view and a sorting option.
When you first open Photos, you see the Main Window with "Photos" at the top. Instead of a button for Albums and a button for Library, you just scoot up, and you see the Library view, or scoot down and see Albums and other collections.
If you go up to the Library view, then at the bottom you will find the sorting menu:

If you choose "Sort by Date Captured," you get exactly the old Library view. If you choose to"Sort by Recently Added," then you get the old Recents view. It's all there, just easier.
There are also a lot of new customization tools to learn about. They threw a lot more stuff in, much of which I'm not interested in, but they also gave us new ways to see only what we want to see.