There are some important factors to consider when defining your resource group:
All the resources in your group should share the same lifecycle. You deploy, update, and delete them together. If one resource, such as a server, needs to exist on a different deployment cycle it should be in another resource group.
Each resource can only exist in one resource group.
Some resources can exist outside of a resource group. These resources are deployed to the subscription, management group, or tenant. Only specific resource types are supported at these scopes.
You can add or remove a resource to a resource group at any time.
You can move a resource from one resource group to another group. For more information, see Move resources to new resource group or subscription.
A resource group can contain resources that are located in different regions.
A resource group can be used to scope access control for administrative actions.
A resource can interact with resources in other resource groups. This interaction is common when the two resources are related but don’t share the same lifecycle (for example, web apps connecting to a database).