To be honest, they sound the same Ive had both.
Check the RMS wattage and see what you can handle from your amp. I dont recall exact specs but if one is 75RMS and the other is 100RMS and yer amp puts out only 75RMS, you go with what you can run/afford.
Infinity speakers are HIGHLY recommended by me, and Ive been through (with friends by proxy) TONS of brands of speakers in my car and the only ones NEVER to warp from sunlight/heat or BLOW are the infinitys i still have.
Sony, sucks. (good HU)
Pioneer, sucks. (AWESOME HU)
Rockford, sucks. (AWESOME AMPS)
JBL, please. (total garbage IMO, keep JBL in yer home theater)
I mean some may flame me for this but I had a set of 6x9 Infinitys on my back dash (in my ol 626) and for 3 years the sun baked them and when I sold the car and removed the speakrs the rubber surround was distorted BUT THEY SOUNDED JUST LIKE THE DAY I BOUGHT THEM. Rockfords I used to have, melted. Pioneers, blew twice. Sony, TOO MUCH MONEY!