An adp is a Microsoft Access Project and is available from Access 2000 and above. The connection to the sql server database is at the project level so there is no need to link sql server tables and ODBC can be completely bypassed. Also, all the Forms and Reports deal directly with sql server data sources. In addition, there is a direct interface to sql server stored procedures and views. You can create and maintain the stored procedures and views directly from Access.
Advantage:
(1) A stored procedure can be a data source on a Form or Report just like you would make a query a data source in an mdb.
(2) Interface to the data source does not need Jet or ODBC
(3) There are many other advantages but the first two are enough to make a difference.
Some confusions (at first look):
(1) There is no direct interface to building queries. A query, if needed, can be built in vba code and stored in the procedures collection. You should NOT use Access Queries since they should be stored procedures on the back end sql server so they are available to all the clients - also more efficient, faster, etc..
(2) A View is an sql server view and resides in sql server.