First Bike: CRF450R and CRF450X... How big is the difference?

Hey guys, this will be my first Dirt Bike, but I have ridden and owned various ATV's both Sport and 4x4. I know most will say that the CRF450 may be too much to handle for my first bike, they are probably right, but I'd like to get something that I can grow into, especially since it's gonna cost around $6,000.

My main question is about the Honda CRF450R and the 450X. My main use for the bike will be trailriding, and the trails I ride on have various terrain, from both close and open woods to open dirt roads, but I'd also like to occasionally go the the mx track. I know that the 450X is a trail bike but I was wondering if it can also be used for an mx bike every-know-and-then? I'd also like to hit some jumps on it, is it well suited for getting air, hows the suspension? Or do you think I should just get the 450R, how does it handle the various terrains? I know the 450R is built for the track, but do you think I could adapt and use it as a trail bike?

I'd also like to know how the two versions compare against each other in regards to horsepower, torque, acceleration, top-speed, etc...

Edit: And what about the CR250r, would it work well for me?

1) your physical size (both height and weight are important) 6'1'' 162lbs, 20 years old
2) How physical / aggressive are you ? Pretty aggresive but not crazy, I know my limits . I am an athletic and strong person, I run and lift weights regularly.
3) what do you plan to ride- MX/SX tracks, woods, fields with friends or ????? Mainly woods/trails, but I will occasionally hit the MX track.
4) Do you have any riding experience? Only on ATV's
5) Do you think you will race ? that depends, probably not though
6) Are you mechanically inclined and will you be doing your own bike work? I can do the basic stuff, as for the advanced stuff my dada can help
7) Do YOU have a preferance to a brand/ motor choice (2 or 4 stroke)? Preferably Honda, and I'm pretty much set on a 4 stroke
8) Do you have a dealer close by your home that you might use and what brand(s) does he carry? Yes, a Honda/Suzuki and a Yamaha dealership
9) How much ($) do you plan to spend on a bike? Around $6,000
10) Do you live in California? no, Texas
11) Your age? 20
12) anything else that you think would help form an opinion dont think so

Thanks guys, I'd also like to know how a CR250r 2 stroke would do :) , I've been reading up o them and some say they are better for the average rider, easier to drive, maintain etc.... maintanence is big for me. How do the CR250r and the crf450 compare in terms of maintanence?