The following are excellent reads even if you think you understand table occurrences.
Well worth creating the example yourself to help understand.
If I have understood correctly and am sure I will be corrected if I am wrong, but a key differential between the table and the table occurrence (TO) is the mechanism by which latter allows the linking together of related tables (specifically their occurrences). These related table occurrences form a Table Occurrence Group (TOG). A Layout uses only one of these TOs and has access to any related field from the entire TOG to which the TO is part of. Presumably being able to link tables differently by creating different TOs and TOG gives improved flexibility. Still lots to learn