hammer drill vs. impact

[chicken89]

I've seen a lot of pictures on here of people with ratcheting drills and no (noticeable) hammer drills. what is the difference between them?
i see there are bits that are "impact ready", but none state "hammer drill ready" so i presume there is a noticeable difference between the purposes.

 

[lametec]

Hammer drills are for drilling holes in concrete.

 

[darwyn]

Both provide sharp jolts of action, the difference is in which direction that sharp jolt goes. An impact driver will give a sharp jolt in the direction of the drill chuck's rotation. The impact action can be very useful for driving screws, and breaking free stubborn fasteners.

A hammer drill moves the chuck in and out, perpendicular to the chuck's rotation. It's like taking a regular drill and pushing it in and out of the hole, but better. If the material is brittle, like cement, the hammer drill will break it up as it is drilling. Hammer drills and wood, less effective.

 

[chicken89]

darwyn: thank you for the mental picture.
makes sense why i see so many pictures on here of people with impact drivers. i haven't read much about people working on/in concrete to be using hammer drills