There isn't really an exact line where a beer transitions into what is commonly called "malt liquor". The obvious distinction is alcohol content, but many specialty beers can have very high alcohol content comparable to that of malt liquor.
As a general rule malt liquor is lightly hopped or sometimes contains no hops. In addition to malted barley being used as a fermentable sugar like in beer, malt liquor includes high amounts of other fermentables like rice syrup solids or sometimes just sugar. American style pilsner lagers also use rice syrup solids to provide a lighter color and body in the finished product, however they use it in smaller amounts thus leading to a lower alcohol content.
So in practical terms, malt liquors commonly found on the shelves of convenience stores is basically an American style pilsner beer that they added a bunch of rice syrup so the alcohol content is higher.
This is conjecture on my part, but it's also likely that brewers speed up the fermentation time of malt liquor by brewing it at higher temperatures than traditional lagers. Yeast can make some pretty off-tasting flavors when not fermented at low enough temperatures. This would speed up the overall brewing time, and this is what probably allows them to create a cheaper product.
As a general rule malt liquor is lightly hopped or sometimes contains no hops. In addition to malted barley being used as a fermentable sugar like in beer, malt liquor includes high amounts of other fermentables like rice syrup solids or sometimes just sugar. American style pilsner lagers also use rice syrup solids to provide a lighter color and body in the finished product, however they use it in smaller amounts thus leading to a lower alcohol content.
So in practical terms, malt liquors commonly found on the shelves of convenience stores is basically an American style pilsner beer that they added a bunch of rice syrup so the alcohol content is higher.
This is conjecture on my part, but it's also likely that brewers speed up the fermentation time of malt liquor by brewing it at higher temperatures than traditional lagers. Yeast can make some pretty off-tasting flavors when not fermented at low enough temperatures. This would speed up the overall brewing time, and this is what probably allows them to create a cheaper product.
