Question

Difference between fixed order quantity and fixed time period

Answer 1

The biggest difference betweenthe fixed-order quantity system and the fixed-time period systems is in the timing and quantities of the orders placed. ... On the other hand, a fixed-period system could ensure that inventory levels are checked on a regular basis for all items—say every two weeks.

Answer 2

A fixed order quantity system is the arrangement in which the inventory level is continuously monitored and replenishment stock is ordered in previously-fixed quantities whenever at-hand stock falls to the established re-order point. In other words it is an Inventory Control Systems.
and The Fixed Period Ordering is an inventory control system, wherein the order for the replenishment of inventory items is sent periodically or after a fixed time interval. It is also called as Fixed Period Deficit Orderingsystem, because every time the order is placed, the order quantity is different.