"Hammer drill" and "percussion drill" are different names for the same tool.
In addition to the rotary drilling motion, they use a pair of cam plates to create high frequency in and out motion of the chuck. This helps when drilling brittle materials like masonry, stone, etc.
Rotary hammers do a similar motion, but instead of cam plates, they use a pneumatic hammer mechanism which is much lower in frequency but with much more power and stroke.
Impact drills are quite different:
They have a mechanism which takes effect at high torque loads which makes the rotation "stutter". There is no in and out motion of the chuck. The effect is somewhat similar to an impact wrench.
The hammer function makes the tool make hits (like a hammer) without rotating. The impact drill means it will make hits and rotate at the same time. Usually you would use a masonry drill bit withe the impact drill function and a chisel for the hammer function.
Both give a percussion action to break stone and concrete.
The SDS drill is considered to be the superior option for efficiency and ease of use, it does not require a chuck key. The hammer drill requires a chuck key for fitting different drill bits, which is considered the main difference of the drills.
Special Direct System drills are heavier than regular drills, have a hammer action and a chiselling action and take larger drill bits and chisels.
That's a tough task for a battery operated tool. You really need a hammer drill. There's a nice Milwaukee cordless hammer drill at Sears but it costs $350. My corded hammer drill cost only $79. To me that is a huge difference for the convenience of cordless.
There is no difference, I drill both frequently with the same drill bits.
Nothing. Both work on the principle of 'hammering' a hole through a material (usually masonry such as brick or concrete) through the action of a drilling action to remove debris and the hammering which breaks down what the drill twist cannot purchase itself. The 'impact'referred to is caused by a cam within the drill that aggressively vibrates the chuck and bit to 'hammer' the material. Twist bits 'carve' out material whereas hammer or impact drills pulverise.
If it fits in the chuck straight, yes you can use it. It will be much more effective in a rotary hammer drill though.
The only difference between a battery drill and a regular drill is the type of power source. A battery drill is one that does not require a power cord, but can only last a finite amount of time.
There are plenty of models of corded drill such as Heavy Duty 240 Hammer Drill and 24V Cordless Hammer Drill with Accessories, Wolf 810 watt 240v Impact Rotary Hammer Drill Variable Speed.
metal drill bit has a finer point
Mainly that one is a drill, and the other, a screwdriver.