SQL Server engine vs. Analysis Services: are they different engines?

We currently run monthly computations using a SQL Server database and SELECT, and store the results in SQL Server.

Before publishing the results, they are validated by a 3rd party, who recomputes the values based on the raw input data, using a program, and compares the results.

We are considering bringing the validation step in-house. The requirement is that we recompute the validation numbers using a "different way", and we are considering SAS.

We are looking at Analysis Services for other reasons, but my current question is: is the underlying engine behind Analysis Services "different" from the SQL Server Database Engine, different enough so that calculations performed via MDX could be considered a "different way" of computing the numbers vs. SELECT.

Thanks,

Dan O