I am trying to get the Service Principal name using the object id. I have used below command
Get-AzADServicePrincipal -ObjectID '7d04df0f-d953-4fac-8b34-fa032b132054'
I got below result
When I check this Service Principal in portal, I got same application id but different object id
What and why there is difference between these 2 object ID's?
I believe you're mixing 2 things. If I am not mistaken, the screenshot you shared is that of your application (from the App Registration).
An Application's Object Id will always be different than that of the Service Principal.
Please check the Object Id of your Service Principal by going into "Enterprise Applications"
In the portal, what you showed is the App Registration i.e. AD App, it is different from the service principal, it is a different object in AAD, so it has a different Object ID, to check the service principal in your tenant, click the Managed application in local directory as below.
Then you can see the service principal i.e. enterprise application.
Reference - https://docs.microsoft.com/en-us/azure/active-directory/develop/app-objects-and-service-principals