As nouns the difference between aerator and tiller
is that
aerator is a device which mixes air with a substance, particularly soil or a liquid while
tiller is a person who tills; a farmer or
tiller can be (obsolete) a young tree or
tiller can be (archery) the stock; a beam on a crossbow carved to fit the arrow, or the point of balance in a longbow.
As a verb tiller is
to put forth new shoots from the root or from around the bottom of the original stalk; stool.