If your business is marketing commodity other than the price. How would you differentiate yourself from competition?

I make sure that I satisfy customers with my commodity.
The satisfaction ratio is more than the price of the commodity

that depend on the prouct itself and the target customer of it.
if they care about the quality then you should stress on that using the advertising tools.
if is a luxurious product then you have to stress on being unique..
what I mean is you have to study your target customer to know what will attract them and highlight it 

I think it depends on understanding the customer orientation if he/she maybe price oriented or quality oriented or whatever the orientation mode of him/her then the mind set of our end user then we can customize and adapt the message accordingly and then you be able to satisfy your customer needs/wants hence i humbly beleive that will differentiate yourself from the competition .

try to retain my clientelle up with a good quality of service, and small business shares (gifts, bonus ....etc)

I will stress on the Item or product benefits which will have a real value to the customer or user. 

Provide  better after-sales service and warranties.

By providing superior quality of products to customers and sale after service.