Firstly,the size and the component is different. Drill has only Motors (rotor + stator) and biting each other and gear turns. Hammer drill is different, should call it "the hammer," because it has impact energy.It can use for concrete, stone and other hard material. So the size is a little larger than the drill, because the hammer drill has the cylinder, rod, piston, and other important parts inside. However,the electric drill can only drill wood, metal, plastic and other materials.
Hammer drill used piston movement and compressed gas to impact drilling,need less effort, can drill 6--100mm holes in the concrete, brick, stone and other hard and brickle material.The hammer drill can not open holes in metal. Drill has not shock, so it requires human have to pressure on the metal, wooden material to drill diameter 6-50mm holes. The advantage is that it has less shock, the precision is high and the price is not high. Beside They use the different drill bits,alloy drill bits and normal drill bits. Both of them can drill holes in concrete structures.