Barnes & Noble (BKS) has announced that some customers who ordered its Nook e-reader will not get their shipments until after the holidays. This could put the retailer at a big disadvantage to competitor Amazon (AMZN), whose Kindle is the most popular e-reader and is still available for holiday gift giving.Barnes & Noble will offer people whose Nooks are delayed a $100 gift certificate.The largest bricks-and-mortar bookstore sent out a notice saying, "If for whatever reason we are not able to ship your Nook in time for arrival by Dec. 24, we will send you an e-mail notification on Dec. 23 with a $100 Barnes & Noble.com online gift certificate to use as you wish at BN.com."

The delay could hurt Barnes & Noble's image. The tardy deliveries may also cause some people to order a Kindle from Amazon to make sure that their gift of an e-reader comes on time.

The news shows the difference between a company where e-commerce is a tiny part of its business and one where e-commerce is at the core. Amazon's Kindle is its largest selling product. It can't afford to run out of the product or ship it late. The same imperative apparently does not hold true at Barnes & Noble.

Douglas A. McIntyre is an editor at 24/7 Wall St.