The Dash Button is a scaled down version of the regular Amazon Dash which can order any product by just saying the product name. It's kind of like talking to Echo. The regular Amazon Dash looks kind of like the Echo remote.
The Dash Button, however, does not respond to voice. It's a physical button that is programmed to buy one specific product that you choose. For example, you can put the Dash Button next to your coffee maker. Whenever you push the button, it will order Keurig, Green Mountain Coffee, Breakfast Blend, K-Cup packs, 72 Count from Amazon.
Or put another Dash Button in the bathroom to order Charmin Ultra Strong Toilet Paper 40 Double Roll (10 Packs of 4 Double Rolls) from Amazon.