Think of navigate like a stand alone gps unit that is tied to all the info that google maps can provided and it can be laid on top. So if you want talking turn by turn directions or not (it can be muted) then go with navigator if you just want to see where you are and where you are going then use google maps.
Like it was stated before, Navigate gives turn-by-turn spoken directions based off your GPS. Maps just follows above you (an optionally shows a suggested course if you use if for directions).
I like navigate better for unknown destinations because of the spoken instructions and you get a 3D layout of oncoming intersections.
Try them both out and see what you like.
I would strongly suggest using Navigate. I used mine for the first time after printing Mapquest but did not use printout at all. Drove over 500 miles going from Memphis to Kansas. Even when you pull off of route to go to store or breaks, the Navigate lady-voice will put you right back on the correct path. Just my two cents......
If you are using Navigation, it seems to use a large amount of power, quickly reducing battery life. Also, make sure you turn it off when you arrive at your destination or it will continue to suck power, leaving you with a dead or near dead battery.
My wife (samsung fascinate with 3500 battery) and I (Dinc with 3000 eBay battery) used both recently on a trip. Even plugged into car charger, the phone seemed to use more power than the charger could supply while using Navigate. Would turn off navigate after reaching our destination and even though plugged into car charger, the batter was lower than it was to begin with. Both phones also got extremely hot. My wifes Fascinate would just shut down, but my Dinc kept working, even up to 127* showing on the battery widget!
Google should WAKE UP! If Google is going to try and compete with the likes of GARMIN and TOMTOM , then it had better get its act together, because so far GARMIN and TOMTOM are making Google Navigation look like a pretty useless kid's game. Try using Google Navigation and GARMIN and/or TOMTOM simulataneously. Within 5 minutes you'll shut of Google Navigation because the GARMIN & TOMTOM will have given you DOZENS of instructions while Google Nav will have given you 5! Google Maps is great but Google Navigation is a kid's toy AND NOW SOME BRILLIANT MORON at Google decided to totally integrate Maps and Navigation which really ****s everything up! Google where DO you find these geni-asses??! :-P