A data mart is a dedicated repository that serves specific needs of a singular business unit or department, providing targeted insights and reports through its structured format. Data marts are ideal for organizations with well-defined analytics needs and focus on fast, efficient reporting. They offer advantages such as high performance, ease of use, and relevance to the specific business unit's requirements. In contrast, a data lake is a centralized repository that stores raw data in various formats, providing flexibility and scalability for big data applications and advanced analytics. Data lakes are suitable for organizations with diverse data types and need for future-proofing, supporting complex analytical processes like machine learning and predictive analytics. The choice between a data mart and a data lake depends on the organization's specific needs, focusing on either fast reporting or big data exploration and scalability.