well
a component is two seperate bits, a tweeter and then a mid woofer, with a crossover to send the correct signals to each, Coax is basically a cheeper option, no crossovers and just a speaker with the tweater intergrated, comps are better quality, but id rather have a top brand coax than a cheepo brand comp if that makes sense
i got rainbow comps up front (they were 400 quid tho)
and i got Focal coax for the back, they were 200 quid and sound fantastic