Ver 8->9 recording List question

Hello guys,
Little question , since the upgrade 8 to ver 9 i have some difference between same structure.

Imagine We have a structure Named sRECORDING_MAIN_ARTIST

When i create a new structure with a substructure with some elements ,and 2 elements A and B.
What is the diférence between the A and the B Element (see the attached image)?

the A is a type of sRECORDING_MAIN_ARTIST Record List
the B is a type of sRECORDING_MAIN_ARTIST List

the only difference is that A is from the upgrade of the ver 8 and B is a new element .

Are they equivalent ?