Example of Price discrimination Can anyone explain why this isn't an example of price discrimination:

The same golf club selling for $100 at Sports Authority and 80 on Amazon.
I believe that consumer's demand elasticity to price at Amazon would be higher than the consumer at certain Sports Authority. May be the idea of an Sports Authority which I've is wrong?

I came across this in a quiz in the Standford online course for Economics.
Price discrimination is when a firm charges different prices for a homogeneous product to different consumers. 

In this example we see no such discrimination among consumers. This is just a case where there is competition between two firms.