Answer
The split isn't fully uniform across every sub-tab — Header/General information is genuinely kept in separate tables for Customer and Supplier (customer_info / supplier_info and similar), and most of the remaining sub-tab data follows that same separate pattern too. However, some sub-tabs, including some Contact, Person, and Communication Method information, are genuinely combined/shared between Customer and Supplier in common tables, while Invoicing information crosses over in a shared identity_invoice_info-style table, Payment information behaves similarly, and Order-tab information stays fully separate. Rather than assuming one single shared table covers everything, the reliable way to find the real backing table for any specific screen/tab you're investigating is to check that screen's own System Info to get its Logical Unit, and derive the table name from there.