Chantix is not a benzodiazapine. It is a medication that partially "binds" to the parts of our brains (the receptors) that really like nicotine. The scientific term for this type of medication is:
partial nicotinic acetylcholine receptor agonist. In the most basic of explanations, the medication fools the brain into thinking that it's already at least partially happy without the drug, nicotine.
It is important to note that Chantix is NOT nicotine. It just tells the brain that it doesn't need so much nicotine any more. Over time, people can actually stop using tobacco products to deliver nicotine to the brain. Once that has occurred, they can eventually come off the medication. This process eases the uncomfortable effects of nicotine withdrawal... which all tobacco users know as the most horrible part of quitting.