I am curious about the difference is when creating an App Service in the reservations for 3 years and just having an App Service Plan which I can add multiple App Services to ?
The cost is much lower than an App Service Plan, but I was wondering if its the exact same concept as an App Service Plan ?
Meaning I can create multiple App Services and have them all in the same App Service Plan ? Or is the Reservation App Service for a single app alone ?
Yes, you can deploy multiple App Services in the same App Service Plan though it is normal or reserved.
You can also create multiple App Services within the same region or across regions supported by Azure in which this flexibility makes ASEs ideal for horizontal scaling feature.
Features of Normal ASP and Reserved ASP were almost same, and you'll get some discount on the Reserved ASP cost.
In the Middle of Reserved ASP, you can increase the Number of instances in that ASP based on your requirement or load balancing.
Refer to Azure App Service Pricing doc and How Reservation works in Azure App Service for more information.