In Google Photos hasn’t had any major interface changes since its inception as a standalone app, with the exception of adding a bottom bar in 2016.
Once you get the redesign, you’ll notice that the search bar at the top has been removed, there is now a heading “Google Photos”, which also lost the menu button.
The number of items in the bottom panel has been increased from four to five, namely: “Photos”, “Search”, “Recommendations”, “Exchange” and “Library”. This means that you have to switch to another tab to search for images, which is the crucial downside of this feature.
The album tab is gone in the redesign. Its content is located in the new section “Library” , which also contains elements that were previously in the menu, such as: device folders, archive , recycle bin, etc.
The interface is deployed as a server-side update, so there’s nothing you can do to get the update ahead of time.