There are generally 3 different categories of juicers: Centrifugal Masticating Slow Turning/Gear/Auger Juicers
Centrifugal Juicers
Centrifugal Juicers are probably the most common, these juicers grind the fruit and vegetables by pushing them against a shredder at a very high speed. The shredder disk/grater, which revolves at about 3600 RPM or faster and is usually very loud. Some people say the heat generated destroys a large percentage of the nutrients and enzymes. I reserve judgement that issue as I thought the juice would have to reach around 47.7C for that to happen. Their main drawback is that they inject oxygen into the juice, causing oxidation which degrades the juice quickly. But they do produce the juice quickly, in our experience they are a pain to clean!
Masticating Juicers
Masticating Juicers Are a little slower than centrifugal juicers but still quite fast. These types of juicers chew the pulp and then push it through a sieve.. Masticating chews pulp to further break down the cell-wall structure.
Slow Turning/Gear/Auger Juicers
Slow Turning/Gear/Auger Juicers These machines turn at a lot slower speed and are generally considered far superior when it comes to retaining as many nutrients and enzymes as possible in your juice. They can be slower to juice but can do basically everything that a centrifugal and masticating juicer can do and more (including making nut butters, deserts, soups and babyfoods), as well as extracting juice from wheatgrass.
Some people seem to refer to all non centrifugal juicers as masticating while other people distinguish between masticating and gear/auger juicers. It seems to me that there is sufficient difference between the two to talk about them separately.
