Data Warehouse / Data Mart

a data mart is a data warehouse that serves the needs of a specific team or business unit, like finance, marketing, or sales. It is smaller, more focused, and may contain summaries of data that best serve its community of users.

Data Warehouse
Centralized, multiple subject areas integrated together.
Organization wide.
Many sources.
Large, can be 100's of gigabytes to petabytes.
Top - Down.
Complete, detailed data.

Data Mart
Decentralized, specific subject area.
A single community or department.
A single or a few sources, or a portion of data already collected in a data warehouse.
Small, generally up to 10s of gigabytes.
Bottom - Up.
May hold summarized data.