Sage SO _Header & SO _HistoryHeader table distinction.

Suggested

I am working on a report (Outside of Sage) to bring all Quotes, Open Orders (Active and Backorder) and Invoiced orders in one report. The report contains fields such as 

Customer No
Order Number
Create Date
Order Date
Promise Date
Promoted Date
Order Status
OrderType
Site#
Part Number
Part Description
Product Line
Product Line Desc
Unit Cost USD
Unit Price USD
Qty Ordered
Qty Shipped
Qty Back Ordered
Extension Amount 

For Header and Line level details on Quotes and Open orders (Active & backorder), they are mapped to SO_SalesOrderHeader & SO_SalesOrderDetail, Invoiced are to the  AR_InvoiceHistoryDetail &  AR_InvoiceHistoryHeader - Is this correct?

 The confusion I am having is when to use SO_SalesOrderHeader / SO_SalesOrderDetail Vs  SO_SalesOrderHistoryHeader /  SO_SalesOrderHistoryDetail table. How are they different?