There are several differences between MDB files and ADP files. The main difference is
1.ADP - the data is stored in an SQL Server table.
2.changes made to the schema (data and structure)are made directly on the SQL Server.
3.Access project is called a project because it contains only code-based or html based database objects pages, macros, and modules.
4.Access project does not contain any data or data definition based objects.
You most like have to change the way your queries are designed, forms can stay the same way (as long as they are base on newly created procedures). Access project gives you a way to create an interface to your data with the full capabilities of access MDB reporting and form features.