the biggest difference are the x-overs. In coaxiles, companies are vary limited in the components they use in their x-overs, usualy just a simple 1st order x-over for the tweeter and they let the mid driver's inductance to take care of the low pass, since the mid is not properly crossed over, this can induce distortion and cancellation between the mid and tweeter. in components, companies are far less limited in the design of the xovers. they can put together a well deigned 2nd order or even a 3rd order xover that goes with the tweeter and mid.