BBird is correct. There is infact a large difference, and it's definitly noticeable.
Do I think it's worth it? Yes and no. Yes being if you have lossless files, it's by far the BEST portable out there....it's rediculous. And along with lossless comes the fact that you lose space REALLY quickly. So a LARGE HD is almost a plus if you want to have any sort of variety. Unless of course, you don't mind switching tracks out like most people with portable players do anyways.
But, if you listen to MP3's, or have a laptop you bring with you for audio, it's probably not a wise investment, seeing as how you have a source you're using anyways that with a soundcard, sounds on par if not better. And if you primarily only use a portable for active activities...you will want a flash based player anyways.
But, I'll tell you this, aside from not being able to use it for active sessions, and if I didn't have my laptop, I'de WHOLE HEARTEDLY recommend it. I more or less bought one just to see what the hype was about. And it is a great PORTABLE. I just think it's a good thing to show you both sides of the fence...