They ride a little differently. The 450 likes to rev up a little more before it's in its happy place.. while the 525 a little more tolerant of low RPM chugging. I would even say the 450 is a bit snappier in the power band area, compared to more linear predictability of the 525. Think of it as a continuum, where your 250 is at one end and the 525 is at the other, you can pretty much plot the 450 about 2/3 the way between them, closer to the 525.
Also the 525 is a little bit quieter than the 450. Those were my takeaways from riding both versions within in the club here.
82 fj40, 99 uzj100, 06 gx470
05 525EXC, 01 XT225, 09 TTR125, 07 TTR90, 07 CRF50