What is the difference between and single stage and two stage snow blower?

Both single stage and two stage snow blowers both have the end goal of removing snow but accomplish this in different ways.
 
Single Stage - A single stage blower used a paddle system to scoop the snow and throw it out the discharge chute in one motion (or stage)
 
Pros: Clear snow to the pavement, light weight for transportation, compact for storage space, very efficient at removing small amounts of fresh snow, paddle system helps assist the blower along.

Cons
: Cannot be used on gravel drives, not efficient at moving large amounts of
snow, limited sizes available, paddles and scrapper bars need replace after 2-3 years.
 


Two Stage - A two stage blower has a metal auger system (first stage) with serrated teethto break down the snow and an impeller (second stage) to throw the snow out the discharge chute.
 
Pros: Can be used on gravel drives, can fight through large amounts of snow fall, have wheel driven self propel, large sizes available

Cons: Heavy and tough to maneuver, not proficient at removing small amounts of snow fall, take up more storage space