Alternative based processing is comparing products based on a number of alternatives.
Attribute based processing focused on a single attribute while comparing different products.
Why is this important to businesses?
Those businesses that seek to attract one or the other may want to design their sites based on the way people scan for information. For example, if someone is using directed search approaches with alternative processes the business may want to highlight the multiple features when compared to competitor products. Those who are browsing the net may be a little more attracted to a specific attribute they can highlight like price or quality.