Why does automotive glass shatter into tiny pieces but glass used in our houses into shards?
Let's start out by covering the
Why?
Glasses used in automobiles are designed to break in tiny pieces.
Imagine you're driving down a dark highway hitting dangerously high speeds and then suddenly you lose control and crash.
If the glass used was not to shatter in tiny pieces rest assured you would not remain in one piece. Essentially it shatters for safety reasons.
Household glass on the is generally not involved in such drastic accidents so there is no need for it to shatter into tiny pieces .
How is it done?
From How Stuff Works

Tempered glass is created by heating and then rapidly cooling the glass to room temperature by ushering it through a system of blowers.
The surface of the glass cools much faster than the center of the glass and contracts, causing compressive stresses, while the center of the glass expands because of its temperature, producing tensile stresses. What does that mean? Imagine a piece of glass that could be pulled or stretched to a certain length (tensile stress), while being pushed down and compressed (compressive stress) simultaneously. Both the pulling and pushing stresses achieved through the heating and cooling process give tempered glass its tensile and compressive strength. The differences between these two give the glass 5 to 10 times the amount of strength it originally had.

This system holds a lot of energy due to the stress so when it breaks all of it is released causing the glass to shatter into tiny pieces
Tl;Dr
Automotive glass contains more energy than normal household glass. When it breaks all that energy is released which causes the glass to break into tiny pieces.