Data Mart and Cubes - In Short:
Data mart is a collection of data of a specific business process. It is
irrelevant how the data is stored.
A cube stores data in a special
way, multiple-dimension, unlike a table with row and column. A cube in an
OLAP database is like a table in a traditional database.
A data mart can
have tables or cubes. Cubes make the analysis faster because it
pre-calculates aggregations ahead of time.
In Detail:
Cube is an OLAP artifact. OLAP cubes can use a different API to a standard relational database. Typically OLAP
servers maintain their own optimized data structures (known as
MOLAP), although they can be implemented as a front-end to a relational data source (known as
ROLAP) or in various hybrid modes (known as
HOLAP).
'Data Mart' is also a
fairly loosely used term and can mean any user-facing data access
medium for a data warehouse system. The definition MAY or MAY NOT
include the reporting tools and metadata layers, reporting layer tables
or other items such as Cubes or other analytic systems.
Traditionally Data Mart is considered as the database from which the reporting
is done, particularly if it is a easily definable subsystem of the
overall data warehouse architecture. However it is quite reasonable to
think of it as the user facing reporting layer, particularly if there
are ad-hoc reporting tools such as Business Objects or OLAP systems that
allow end-users to get at the data directly.
http://stackoverflow.com/questions/360900/datamart-vs-reporting-cube-what-are-the-differences