Not one, not two, but three different things called Google wallet, and four different things called Google Pay, one of which was formerly called Google wallet and one of which went on to be called Google wallet.
Well this explains why every time I get payment autofill suggestions from Google it's a random one of four or five possible auth flows, and pulls from an arbitrary one of at least two separate data sources with different sets of cards saved...
To be fair to them, the diagram makes it look worse than it actually was. From the user perspective, you got your Google Wallet app replaced by a Google Pay app which got replaced by a Google Wallet app. They all work the same (the last one has an extra tab for transit cards), had the same data/information (loyalty and bank cards), and even look pretty similar.
Yeah, it was dumb having your app change names and slightly looks, but materially, little changed.
... wat? Are you suggesting Google has two different services both called Google wallet?