In MT you are basically sharing a Server with other Epicor Customers. So you can’t go crazy on your Customizations and in many occasions must submit certain Advanced Code for Approval to the SaaS MT Team.
Unlike Dedicated Tenant, or for me I am On-Prem - we have the entire Server with all files on-prem and I can clone it, and I can place debuggers, sniff traffic with Fiddler to reverse-knowledge learn stuff.
See the Multi-Tenant Section:
Single Tenant
If my family rents an entire house, we are the single tenant that uses the entire house. In the case of Epicor, being single tenant means only my company uses the VMs. Epicor’s single tenant users have been hosted at providers like RackSpace or CyrusOne. In the Epicor model, the customer is responsible for upgrading the software they purchased and they are the only customer in the SQL Server instance.
Multi-Tenant
Like an apartment building, multiple tenants occupy the same application. Epicor’s first example of this was called Epicor Express. It was created for smaller companies with little or no IT staff. To simplify management, Epicor put multiple companies into the same DATABASE, not instance. Eventually, this morphed into the Multi-tenant product. The problem with MT was having multiple companies in a single database created a bit of a coding mess . This is why MT users cannot use Custom Code. DbContext does not respect company or plant security! Epicor has not sold the MT product for many years now.
Dedicated Tenant
To address the weakness of MT, Epicor created the concept of Dedicated Tenancy. We are still sharing a VM and a SQL Server instance but each company gets its own dedicated database. So now, all the issues that plagued MT have gone away. Unfortunately, as long as Epicor maintains MT users, it has to carry the stigma of the issues that come with it. IMHO, MT has damaged Epicor’s ability to sell the cloud to many companies and continues to be an anchor dragging them down.
Epicor moved both the Mutli-tenant and Dedicated tenant users away from providers like CyrusOne and RackSpace to Azure’s public cloud. This is why the Dedicated Tenancy product is now called Epicor Public Cloud.