<p>Is there a trade off in respect to performance, trade off in respect to memory consumption?</p>

Yes, absolutely a DataTable consumes more memory than a List.
The DataTable class has lots of objects for column definitions, the table info (name, etc), collections of row objects, the "item arrays" for each row (which is basically all the List would have), etc.
EDIT: Also, List is more performant for adding items, itterating through, etc. (reflect the code for "Add" for generic lists, and for data tables to see more detail).