Google Cloud Datastore :
A highly scalable NoSQL Database for your web and mobile applications.
It's simple and integrated, it provides a restful interface through which data can be easily accessible by any deployment target.
You can build solutions that span across the Google App Engine and Google Compute Engine.
App Engine is a service for hosting web applications
Compute Engine is an IaaS service for hosting infrastructure-based services.
Google Datastore is fast meaning that we can focus on provisioning and load anticipation
It also has another feature of Elegant Query, using a schemaless database allows the fastest searching across multiple properties and sort as needed.
It has high scalability, it scales seamlessly and automatically allowing for high performance even with growing traffic.
Firebase is Google’s mobile development platform.
It helps you build apps and growing user-base.
It is used by client-side app developers(both web and mobile).
It is used for building a new mobile app, augmenting an existing app with new functionality and growing an audience.
The Firebase SDK(Software Development Kit) allows you to write mobile and web apps without running your own back-end. You can read from and write to the Firebase Database directly from your app, no server code required. The database security model allows fine-grained access control without a server based on your users.
The Firebase Database stores the JSON object.
A Firebase Project is also a GCP project.
A Firebase project is also a GCP project that uses Firebase services. That is: Billing and Permission for projects are shared across consoles. Unique identifiers for a project like(Project ID or Project No.) are shared across consoles.
Please note that since the underlying project is the same for both Firebase and GCP, if you delete the project using either Firebase or the Cloud Console, it releases all the resources used within the project. It releases all the VM instances, storage(Buckets), databases, applications, Firewall Rules, VPC network, etc that you created.