Vodka, gin and whiskey are defined first by distillation proof and then by production characteristics such as location of production, aging methods and ingredients according to Joe Alecci, lead distiller at Bone Spirits.
For the official definitions that are part of the federal labeling requirements, look up CFR 27 Section 5. Or, if you don’t want to be too official, take a gander at Alecci’s paraphrased primer .
Vodka
Distillation Strength: at least 190
Percentage alcohol: at least 95
Other requirements: None
Insider Information: “The alcohol used to make our vodka is 192 proof.  From there we just add purified water to drop the proofs down to 80 and put it in a bottle. From a business perspective, it is my favorite spirit to handle because the moment it’s distilled it is ready to bottle and put into the marketing chain, so it generates revenue immediately unlike whiskies that have to age for years before they can be sold.”
Name Calling: “Smith’s Vodka is a direct reference to our home base in Smithville.”
Gin
Distillation Strength: at least 190
Percentage alcohol: at least 95
Other requirements:  Must contain juniper berries as a flavoring.
Insider Information: “In Texas, Ashe juniper is synonymous with cedar. Our juniper berries are ‘imported’ from my front yard in Red Rock.”
Name Calling: “We were trying to name our gin when Jeff [Peace] got a call from his wife, Carrie. She is usually a happy, easy-going woman, but on this particular day they had an ‘escalated’ conversation. When he hung up, he fumed, ‘I don’t care what we call the gin, but it needs to have ‘moody’ in the name.’ June is for Juniper. Moody June just had a ring to it.”
Whiskey
Distillation Strength: 160 or less
Percentage alcohol: 80 or less
Other requirements:  depends on the sub-category of whiskey. They include: bourbon, corn whiskey, Scotch, blended whiskey, rye whiskey and Canadian whiskey. Bone Spirits makes Bourbon and Corn Whiskey.

Bourbon: must be made in America with mash that is at least 51 percent corn and aged in unused, charred white oak barrels.
Insider’s Info: “Jeff didn’t want a ‘wheated’ whiskey, so instead of the traditional corn, wheat, barley mash found in many bourbons, we used a corn and rye blend. With the rye influence, it’s reminiscent of a Canadian whiskey.”
Name Calling: “The name Bone Bourbon hopefully is self-explanatory.”
Roll out the Barrel: “We don’t reuse our oak barrels to age bourbon, but we do use them to age other spirits such as gin. The charred oak lends a unique color and flavor to our gin. Because of the darker color, we call it Dirty June. This name has absolutely nothing to do with Jeff’s wife.”

Corn Whiskey: must have at least 81 percent corn in the mash and aged in unused, uncharred oak barrels.
Insider’s Info: “We use 100 percent corn in our mash and do strict single barrel bottling, which means there are only 300 bottles from each 53-gallon barrel batch.”
Name Calling: “Fitch’s Goat was inspired by an ongoing controversy involving the Peace children and their former elementary school principal. One day the situation reached a high pitch, and Carrie called Jeff. She said, ‘Jeff, I want you to go to that school and get Fitch’s goat.’ Fitch’s Goat sounded like a good name—and it looked equally good when we wrote it on the brainstorming board.”
Moonshine
Proof: Unspecified
Percentage: Unspecified
Other requirements: None
Insider’s Info: “Moonshine traditionally referred to illegal spirits. Today, there is no legal definition, although distillers are required to include what it’s made of on the label. In our case, Fitch’s Goat Moonshine is unaged, 100 percent corn whiskey—as per the label—that purposely has a raw edge.”
Name Calling: “We got Fitch’s goat so badly, our moonshine bears the principal’s name, too.”