Home audio drivers vs. car audio drivers

Just kinda curious,

Drivers seem to be specifically made for either Home Audio or Car Audio.

What exactly is the criteria that seperates these>

I see alot of good speaker manufacturers making home audio AND car drivers. Focal, Infinity, ETC, ETC.

I hear alot of problems from DIY'ers about matching tweeters and midrange drivers, was curious if anybody ever messed around and tried building a set of 2 way speakers using infinitys $200 Reference Kappa Component sets.

Is there an actualy difference between car audio and home audio? Is there a different approach to design? Ive seen car audio drivers that run in the thousands of dollars, i know enough about car audio to know that they put ever bit as much of engineering in those products.

or is it basically the fact that most car audio speakers run at 4 ohms while home audio speakers run at 8ohms?