How does a typical electric garden blower vac work?

Here is an illustration of an AL-KO electric blower vac. It is fairly typical in shape and function to many domestic electric blower vacs, where the suction and blower channels are set in the same housing, tube or hose. In a petrol model the blower and suction functions are normally separated and there are replaceable tubes and inlet/outlets for each function 

The main functions have been highlighted. 

And here is the same AL-KO blower vac, this time in a cut-a-way illustration. Note the two separate channels in the tube for blowing and suction, the dividing area that separates the lighter, shreddable items from the heavier items and the impeller which carries out the shredding.