Vodka (Polish: wódka, Russian: водка) is a distilled liquor.

Vodka, one of the world's most popular liquors, is composed solely of water and ethyl alcohol with possible traces of impurities and flavorings. Vodka is made from any one of these fermented substances: grain, rye, wheat, potatoes, or sugar beet molasses.

Vodka’s alcoholic content usually ranges between 35 to 50 percent by volume; the standard Russian, Lithuanian, and Polish vodkas are 40 percent alcohol by volume (80 proof).

Historically, this alcoholic-proof standard derives from the Russian vodka quality standards established by Tsar Alexander III in 1894.
The Muscovite Vodka Museum reports that chemist Dmitri Mendeleev determined the ideal alcohol content as 38 percent; however, because in that time distilled spirits were taxed per their alcoholic strength, that percentage was rounded upwards to 40 percent for simplified taxation calculations.

For such a liquor to be denominated “vodka,” governments establish a minimal alcoholic proof; the European Union established 37.5 percent alcohol by volume as the minimal proof for European vodka.

Vodka is traditionally drunk neat in the vodka belt — Eastern Europe and Nordic countries — and elsewhere. It is also commonly used in cocktails and mixed drinks, such as the bloody Mary, the screwdriver, the White Russian, the vodka tonic, and the vodka martini.

Source: http://en.wikipedia.org/wiki/Vodka

Flavoured vodkas includes all spirits, which besides spirit and water additions includes aromatic substances, called aromatic - flavor admixture, giving them taste and odor characteristic for their species concerned. In addition, they contain mostly sugar and sometimes food coloring. Their power ranges from 20 to 75%.

A liqueur is an alcoholic beverage that has been flavored with fruit, herbs, nuts, spices, flowers, or cream and bottled with added sugar. Liqueurs are typically quite sweet; they are usually not aged for long but may have resting periods during their production to allow flavors to marry.

The word liqueur comes from the Latin liquifacere ("to liquefy").

A distinction can be made between liqueurs and the kind of cordials that are made with fruit juice. In some parts of the world, people use the words "cordial" and "liqueur" interchangeably.

Liqueurs date back centuries and are historical descendants of herbal medicines, often those prepared by monks, as Chartreuse or Bénédictine. Liqueurs were made in Italy as early as the 13th century and their consumption was later required at all treaty signings during the Middle Ages.

Nowadays, liqueurs are made worldwide and are served in many ways: by themselves, poured over ice, with coffee, mixed with cream or other mixers to create cocktails, etc. They are often served with or after a dessert. Liqueurs are also used in cooking.

Some liqueurs are prepared by infusing certain woods, fruits, or flowers, in either water or alcohol, and adding sugar or other items. Others are distilled from aromatic or flavoring agents. The distinction between liqueur and spirits (sometimes liquors) is not simple, especially since many spirits are available in a flavored form today. Flavored spirits, however, are not prepared by infusion. Alcohol content is not a distinctive feature. At 15-30%, most liqueurs have a lower alcohol content than spirits, but some liqueurs have an alcohol content as high as 55%. Dessert wine, on the other hand, may taste like a liqueur, but contains no additional flavoring.

Anise liqueurs have the interesting property of turning from transparent to cloudy when added to water: the oil of anise remains in solution in the presence of a high concentration of alcohol, but crystallizes when the alcohol concentration is reduced.

Layered drinks are made by floating different-coloured liqueurs in separate layers. Each liqueur is poured slowly into a glass over the back of a spoon or down a glass rod, so that the liquids of different densities remain unmixed, creating a striped effect.

Source: http://en.wikipedia.org/wiki/Liqueur