discriminator

noun

1. A person who discriminates or differentiates.

2. A test or variable, etc. that serves to distinguish between different things.

   Colour is not an effective discriminator when it comes to the spiciness of food.

3. Any of several electronic devices that convert some property of a signal into an amplitude whose value is proportional to the difference between the value of the input signal and that of a standard.

4. A feature of the seller's offering that differs from a competitor's offering and is important to the buyer in question.