There are many benefits of using an order management system and operational impact really depends on the organization that is implementing such a system.
Some of the more common benefits are;
Reducing order management workload
Automating communication to and from the channel in the form of order import, stock availability updates, and fulfillment updates (tracking numbers).
Uniform policy management for eCommerce related to shipping, returns, inventory availability, and special requirements.
Data connectivity and the ability to tap into analytics to boost KPI performance or lower costs.