Follow the differences between FO and MDF objects:
MDF vs. Legacy Foundation Objects
There are many similarities between MDF Foundation Objects and Legacy Foundation Objects. Both serve to provide foundational data that organizations can use to structure their companies. Both provide the ability to store attributes on the object level that can be referenced or propagated to the employee’s job and compensation records.
However, MDF and Legacy Foundation Objects are built on two separate platforms, which result in different ways of accessing, configuring, and managing the objects and corresponding data. Below is a table which summarizes the key differences between the two object types.
In addition to the differences in maintaining the tables and data, there are vast differences in the supported functionality and capabilities of the two object types. All functionality that is supported for Legacy Foundation Objects is supported for MDF Objects (associations, field-level configuration, picklists, and so on). However, the opposite is not true – all functionality that is supported for MDF Objects is NOT supported for Legacy Foundation Objects. MDF Objects contain a plethora of additional supported capabilities, including the support of business rules, field-level permissions, and more. MDF Foundation Objects and MDF Generic Objects are created and maintained under the overall MDF platform.
You can find the reference in our guide.
I hope this helps!