Just don't go there.
No, the bigger boys shouldnt have been so dismissive of you. They're only wheeling out the same shitty put downs from the last time someone admitted to being young, they weren't that funny the first ten times either.
Yes, its great you're keen and want to know more at such a young age.
Yes, you could have found out all the information on the internet.
No, its not really a problem you asked.
If you want to stick around here and not have the piss ripped out of you every time you post you need to learn when to just suck it up and stay quiet. Get the information you want, say thanks and don't rise to the bigger boys who are literally trying to get a rise out of you for kicks.
If you really want to get geeky about chassis codes theres loads more information out there, not only the differences between 180 / 200 / 240sx models but all of the S13 KPS13 RS13 RPS13 and so on. Just google S13 chassis codes and eat your heart out.
At the end of the day, those things matter very little. It will either be the shape you like with the engine you like or it will be something else.