Can you explain more. Is there any big difference in 2 way and 3 way?
No, not in a car and not in a casual listening atmosphere.
There are a couple (separate) things going on here:
The difference between components and integrated
The difference between 2way and 3way
He has components in the front, which is the woofer (big speaker) down in the door and tweeters (the little speakers) somewhere else (like up in the A pillar, for example). Installers do that for placement and focusing. The larger the speaker, the more omni directional sound is; the smaller the speaker the more directional the sound is (think of those huge subwoofers thumping away in people's cars that you can feel/hear in your own car--but you can't hear the voices unless the windows are down in both cars).
So woofers can be placed in the door without too much compromise on sound but the little tweeters need to be pointed at your ears for best results, which is why they're mounted up by your head in modern, factory locations.
The backseat isn't as important in getting that precise placement, usually, so integrated speakers are used (woofers with tweeters in the middle of them slightly off-center). That's what he has in the back. I have components in the back but setups like that require more precise placement than just having the whole setup in the panel.
The distinction between 2 and 3 way speakers comes down to how many speakers are part of the system (independent of whether they are composite or components). So far we've been discussing 2 way speakers and those are by far the bulk of car audio options for general applications. A woofer + a tweeter are what you are used to and makes placement simple. A three way speaker will usually add a midrange driver. You then need to figure out where you're going to place that third driver, how to EQ it, a more complex crossover (which also needs correct placement and additional cost), and whether the type of music you listen to even warrants its inclusion. It's main purpose is to reproduce sound better than the other two speakers with this dedicated, to-purpose speaker that can allow them to better focus on the slice of frequency they are best at.
Then there are other factors like a good 2 way is going to outperform a mediocre 3 way, but that's the gist of it.
So you're basically looking at 2 way components in the front to replace what you have in the door and pillar, and then 2 way non-components in the rear to replace the speakers in the door cards.