commerce_line_item VS field_data_commerce_line_items Right now, I am touching the database for drupal 7. I searched about the difference between "commerce_line_item" table and "field_data_commerce_line_items" table. But no luck.

Does anyone know the difference between them? Also, is there any reference that I can follow to check the table explanation?

I really appreciate anyone's help. 

UPDATE

Based on everyone's help and my own opinion, I drew a simple diagram for these two tables:
My answer concerns the structural and not the semantic difference between the two.

The table field_data_commerce_line_items corresponds to a standard drupal field. On the other hand commerce_line_item is a table that is managed by one of the modules in the commerce module family.

The table field_config_instance describes the relationships between drupal fields (which are actually tables such as field_data_commerce_line_items) and higher level entity types (i.e. node) and bundles (i.e. content type) that reference them.