They show two different client side storage mechanisms. WebDB and IndexedDB. The web one is SQLite, it exists right now on most of the modern browsers. Index

They show two different client side storage mechanisms. WebDB and IndexedDB. The web one is SQLite, it exists right now on most of the modern browsers. IndexedDB is what they're planning on implementing, if you read the article, it's essentially the basis for something like CouchDB.