Despite their comparable origin stories, it's important to remember that gin and vodka are two distinct products. Vodka is a neutral grain liquor, while gin is a neutral grain liquor with botanical ingredients. Gin should be infused mainly with juniper berries. This is according to the law, otherwise it cannot be called gin.
Vodka, on the other hand, doesn't need to be infused with juniper berries or anything. There are also differences in flavor and serving. They all have different flavors, production methods and ingredients, but they're worth trying if you haven't tried a wide variety of gins. The United States government officially classifies gin as spirits with a characteristic main flavor derived from juniper berries produced by distilling or blending liquors with juniper berries and other flavors or extracts derived from these materials.
So what's the difference between gin and vodka? Gin is often associated with herbal and pine notes, while vodka is best described as a flavorless entity. Both gin and vodka can be made with anything, but some common bases include corn, wheat, rye, potatoes, grapes, and sugar beet. This gives them less than the 37.5% alcohol needed to be classified as gin, making them a gin-based liqueur. Infusing vodka with juniper berries is only done at home, since it's the easiest way to make a gin, but it's not done on a large scale.
However, in Russia and Eastern Europe, where liquor originated, people consume more than triple that amount. The most obvious thing is that gin is associated with pine and herbal flavors, while vodka is often positioned as odorless and tasteless; however, the two liquors are still very similar. Gin is England's national liquor and there are few things more English than a refreshing gin & tonic. Superficially, you can easily distinguish between gin and vodka, because of the pine flavor that vodka obviously lacks.
Gin is one of my favorite liquors and I have spent most of my time over the past 10 years teaching people about its history, production, virtues and cocktails. It was first only produced in the City of London and, therefore, this style of gin is still known today as London Dry. And some of the best-known cocktails that include gin are gin tonic (duh), Negroni and martini (which was originally made with gin, not vodka, so saying gin martini is wrong and redundant).