I can't really decide what I think on this. The m6300 doesnt look to have a numberpad, which the m1730 has, but it does have 800mhz processor, which the m1710 does not have. Thus, I tend to think it may not be build off of the same platform as either of those... Perhaps Dell decided to make Vostro instead? I really don't know, but I will definately be looking into everything I can possibly think of (short of buying one of each, which I'd love to do were I rich enough) to figure out what kind of parts swappage we can do in the future.
What ACHILLES told you is right,they are different laptops,as is the Vostro 1700 and XPS 1710.
It looks like you can forget part interchanging on the new models like the last few generations,so you might want to just pick the one that suits your needs/looks the best and go with that.