You say celery root, I say celeriac

So what's the difference between celery root and regular celery?  The celery we get from the CSA doesn't look that much different from the top of the celeriac.  The weekly newsletter tells us that the root "is the only part used for cooking purposes" though.

• Broccoli
• Celeriac
• Cilantro
• Collards
• Garlic
• Hot peppers
• Lettuce
• Peppers
• Sauce tomatoes
• Tomatoes
• Butternut squash