Going to have to chide the Japanese for blowing it on translating terms.
The pictured Hitachi is, without a doubt, a hammer-drill. And, yes, there is a forward hammering motion when set in the 'hammer' mode. That motion might not be visible; it's created by a simple mechanism that can best be described as two poker chips riding atop each other. That's the noise you hear.
"Fine Homebuilding" currently has a 'special issue' out devoted to tools. They have within all manner of explanation and pretty artwork describing the impact driver.
