In complete mode, Resource Manager deletes resources that exist in the resource group but aren't specified in the template.
In incremental mode, Resource Manager leaves unchanged resources that exist in the resource group but aren't specified in the template. Resources in the template are added to the resource group.
Sections of an ARM Template
Parameters
Variables
User-defined functions
Resources
Outputs
CLI/Powershell
When using the Powershell command New-AzResourceGroupDeployment with a remote ARM template use the -TemplateUri parameter