@Richard Chua Thank you for your question regarding managing Azure App Service Managed Certificates.
The big difference for Azure App Service Managed certificates is that they are issued by DigiCert, Inc. In your above screenshot, DigiCert is listed as the issuer. This is mentioned in the documentation here. For purchased certificates from Azure (standard or wildcard) Wild West Domains should be the issuer of the certificate.
A less reliable way to check is via the thumbprint of the certificate. Below is a managed certificate (free) that I created. This thumbprint is unique to managed certificates and will not overlap with any paid certificates that you may have. The product group is working on removing thumbprint IDs from the portal to avoid customer confusion as there have been a number of times where customers have hardcoded this thumbprint into their code (not supported) and when we change the thumbprint, their apps break.
I hope these two clarifications help provide you some confidence as you go about managing your certificates. If you have any further questions, please reply here.