A Data warehouse is a collection of data that has been separated from operating systems. This assists a company with their decision-making process. A data mart is a segment of a data warehouse dedicated to a certain business line. Data marts are repositories of condensed data gathered by an organisation for study on a certain subject or entity.
A data warehouse is often more than 100 GB, whereas a data mart is normally smaller than 100 GB. The architecture and utility of data marts are comparably easier due to the discrepancy in scope.