first off the alpine has no internal amp, so you will have to provide one. im pretty sure you were aware of this.

the pioneer has an organic display, where as the alpine has a 3 color dot matrix like display.

the alpine has a slightly higher FM sensativity, 9.3 vs. 9

alpine also has a higher SN ratio, 105 vs. 94 dB

the alpine also has a lower retail price.

check these out:
alpine

pioneer

i wish i had to make the decision of adding one of these two to my car. personally i like pioneer but not that model.

good luck, have fun