File 1: 70 columns - the least amount of columns you need to have in your CSV file to import your orders. This file includes information about: Order, Order Item, Payment, Address.
File 2: 124 columns - contains all the columns in file 1 with extra columns to fill in information about: Invoice, Shipment, Credit memo.
File 3: 590 columns - contain all the fields to enter every single information about an order in Magento Community Edition.
File 4: 716 columns - this is the file 3 version for Magento Enterprise Edition Users.