The rules for using the website introducing the services, its access and its use through the website; and
The legal relationship for the website operator and its users.
This document is drafted to be included in the website
The terms and conditions for using the App including the definition, conditions of use, availability and system requirements for the App.
The legal relationship between the App provider and its users.
They have been drafted to address specific needs either in the Website or App, but as you can see, the documents are related.
If you have a website and a mobile app, you could use both documents.