So, let's see, one is going to take twice as long to get the job done, doing nothing during that time, and leaving you without a driveway, yet is charging more?
I'd ask for an itemized list of the materials they are including in the cost, labor costs, how many people will be on the crew to do the job, and what equipment rentals/fueling is included in the quote. One could be skimping on materials, or one might be paying their crew better wages/insurance, one might own all their own equipment while the other has to rent some of it by the day or hour (I'd lean toward the one who owns their own equipment if that makes a difference...it could sway the cost either way, depending on what equipment it is...might make it cheaper to have bought it outright rather than continually renting, or may make it more expensive to be paying out the loans for the equipment purchase...but, if they own their own equipment, no delays on the job waiting for rentals to be available).
The other thing to check is their math that they aren't over-ordering materials. If the one that is more expensive tells you it's going to be two layers of asphalt 2" deep each, and has the square footage of your driveway figured out, you can check that the cubic yards of asphalt they're going to use adds up (there should be SOME excess to account for spills, and rough estimates of driveway size that could be slightly off), but you don't want it to be a whole 'nother driveway's worth of excess). Otherwise, you might be paying for the contractor's brother-in-law's driveway too, or some such.
A few other things to consider. Check that the lower priced one is a binding quote...if they need more materials or it takes longer to do, the price isn't going to start going up? In other words, when you have a finished driveway, all you're handing them is a check for $3000, and they won't be tacking on extras that didn't go into the quote?
Are you in a remote location or have a particularly difficult driveway to access? The higher quote could be from someone who for some reason doesn't really want to do the job you have...maybe too far from other customers that it's difficult to get out your way without losing a lot of travel time, maybe something as simple as worrying you or your wife will have a conniption fit if flower beds alongside the driveway are damaged and don't want to deal with it? Sometimes contractors who don't really want a particular job for any number of reasons but don't want to piss off people by refusing the work outright will just give an exorbitant quote that will make it worth whatever hassle they are anticipating if they end up taking the job.
Or, the higher priced one might be anticipating rising costs of the raw materials, or has already been hit by some of those costs on prior jobs, and rising fuel costs, and is building in a buffer or even trying to make up for losses by raising prices. Check with both that if cost of materials go up between now and when they do the job, who eats it? Some contractors give estimates that fix the cost of labor, but only estimate materials, and if the materials costs go up, you're going to pay the higher price. Others give you more of a fixed price for everything, so if materials costs go up, they absorb that expense but if they go down, they reap more profit, and may give a higher estimate so they know they can make a profit even if materials go up.
So, as Evo suggested, I'd ask them flat out to explain everything in their quotes because you have two that are so wildly different from one another.
And, if you have references of people who have had driveways done by both, find some of the oldest ones (ask about ones done 5 years ago) and drive around seeing what they look like now.
