Google has launched standalone Docs and Sheets apps for iOS and Android, letting you create and edit documents and spreadsheets on your mobile devices. Slides app, which will let you do the same to presentations, is coming "soon."
Why standalone? Because Google already offers the Drive app, which lets you store and manage your files as well as create and edit documents and spreadsheets as well as view presentations and PDFs.
Now, the company is splitting those functionalities in a separate app for each purpose. You can now get them in the App Store (Docs, Sheets) and on Google Play (Docs, Sheets). And if you just continue using Drive for editing documents and spreadsheets, you will be prompted to download the standalone apps over the "next few days."
The apps have offline support, meaning you can create, view and edit files without an Internet connection. And, when you open the new apps, you'll see your most recently edited files.
As for Drive, you will still be able to view and organize all your documents, spreadsheets, presentations and photos through that app.