Question: What make single malt different?

Single malt Scotch


Single malt Scotch is single malt whisky made in Scotland. To be a single malt scotch the whisky must have been distilled at a single distillery using a pot still distillation process and made from a mash of malted barley. As with any Scotch whisky, a single malt Scotch must be distilled in Scotland and matured in oak casks in Scotland for at least three years and one day. (Most single malts are matured longer.)
"Malt" indicates that the whisky is distilled from a "malted" barley. Several types of grains can be malted (for example, barley, rye and wheat are all grains which can be malted); however, in the case of single malt Scotch, barley is the only grain used.
"Single" indicates that all the spirits in the bottle come from a single distillery. Bottlings containing malt whisky from multiple distilleries are called "blended malt".
Until the Scotch Whisky Regulations 2009 (SWR 2009), the word "blended" only appeared (in the context of Scotch whisky) on bottles of whisky that contained a mixture of both barley and non-barley grain whisky, but this is no longer the case. Under the terminology established by the SWR 2009, the term "blended malt Scotch whisky" replaced the term "vatted malt" to describe a mixture of single malt Scotch whiskies (malted barley whisky).  A mixture of malted barley whisky and non-barley whisky is labeled "blended Scotch whisky" (without the word "malt"). 
The age statement on a bottle of single malt Scotch is the number of years the whisky spent maturing in casks.  Very few whiskies are bottled from a single cask, and the mixing of spirits with different amounts of ageing is allowed; the age statement reflects the age of the youngest whisky in the mix.
History
Distillation of whisky has been performed in Scotland for centuries. The earliest written record of whisky production in Scotland from malted barley is an entry on the 1494 Exchequer Rolls, which reads "Eight bolls of malt to Friar John Cor, by order of the King, wherewith to make aqua vitae."
In the following centuries, the various governments of Scotland began taxing the production of whisky, to the point that most of the spirit was produced illegally. However, in 1823, Parliament passed an act making commercial distillation much more profitable, while imposing punishments on landowners when unlicensed distilleries were found on their properties. George Smith was the first person to take out a licence for a distillery under the new law, founding the Glenlivet Distillery in 1824.
In the 1830s, Aeneas Coffey refined a design originally created by Robert Stein for a continuous still which produced whisky much more efficiently than the traditional pot stills, but with much less flavour. Quickly, merchants began blending the malt whisky with the grain whisky distilled in the continuous stills, making the first blended Scotch whisky. The blended Scotch proved quite successful, less expensive to produce than malt with more flavour and character than grain. The combination allowed the single malt producers to expand their operations as the blended whisky was more popular on the international market. As of 2004, over 90% of the single malt Scotch produced is used to make blended Scotch.
Most distilleries in Scotland are not owned by Scots. The Japanese beverage company Suntory owns Morrison-Bowmore, while other international companies, such as LVMH & Pernod-Ricard (France), and Diageo (England), own the majority of distilleries. The largest distiller to remain under Scottish ownership is William Grant & Sons, owned by the Grant family, with headquarters in Motherwell, Scotland. Other distilleries owned by Scottish companies/families are Glenfarclas, Kilchoman, and Daftmill.
Regions

Flavour, aroma, and finish differ widely from one single malt to the next.
Single malt Scotch whiskies are categorised into the following whisky-producing regions: Highland single malts,  Island single malts  (A sub-section of the Highland region), Speyside single malts, Islay single malts, Lowland single malts, and Campbeltown single malts.
Independent bottlers
Independent bottlers buy casks of single malts and either bottle them immediately or store them for future use. Many of the independents began as stores and merchants who bought the whisky in bulk and bottled it for individual sales. Many distilleries do not bottle their whisky as a single malt, so independent bottlings are the only way the single malt gets to market. The bottling process is generally the same, but independents generally do not have access to the distillery's water source, so another source is used to dilute the whisky. Additionally, independents are generally less concerned with maintaining a particular style, so more single year and single cask bottlings are produced.
Established independent bottlers include Duncan Taylor, Master of Malt, Murray McDavid, Douglas Laing & Co, Signatory, Hart Brothers, Cadenhead's, and Blackadder.
See also
List of distilleries in Scotland
Single malt whisky
Whisky