Tabular models differ fundamentally from traditional multidimensional cubes in how they handle data:

in Microsoft SQL Server Analysis Services (SSAS) is a relational database approach that organizes data into tables and columns, similar to Excel or standard SQL. It is powered by the xVelocity (VertiPaq) engine , an in-memory storage system that uses advanced compression and multi-threaded processing to deliver high-speed query performance. Core Architecture and Storage

Tabular modeling overview - Analysis Services - Microsoft Learn