Scrapbook supports 3 different interfaces. There's the Scrapbook-specific KeyValueStore, and then there are 2 PSR interfaces put forward by the PHP FIG.
An interface for typical key-value store functionality inspired by PHP's Memcached API. Implementing this interface in an application means you get support for every backend for free, since all adapters share this exact same implementation.
The PHP-FIG (Framework Interop Group) have defined this pool driver cache standard. Scrapbook has an implementation that builds on key-value-store, so it works with all adapters.
psr/simple-cache is a PHP-FIG (Framework Interop Group) standard for a driver model cache implementation. It's a relatively simple & straightforward driver model interface, very similar to KeyValueStore.