Let me start by saying that cold air intakes and short ram intakes both have their pros and cons. That being said, they are also very similar. The Short Air Intake System, AKA as a Ram Air Intake or Cold Air Induction, is a system that will utilize some type of external scoop that faces forward on the vehicle. Normally, it works with a pair of snorkels or a single hood scoop through which fresh air enters. Now the Ram Intake does exactly what it sounds like. As you start driving, fresh air is "rammed" through your hood, forced down the intake manifold, and filtered through the air cleaner. Once you hit thirty five mph, this intake system will act similarly to a turbo charger; taking in more and more air to increase your horsepower. Oh yea, and they are much cheaper.
Let's look at Cold Air Intakes. The Cold Air System replaces your stock air cleaner box and its plumbing with a simple tube that relocates the air intake to a position where it is picking up cold air from outside the engine compartment. This system consists of a large tube that allows greater airflow capability than the stock filter system. I've noticed that people have expressed concerns about water penetrating their engines with this system. First, it is HIGHLY unlikely that this will ever be a problem. Rain and water droplets are no problem. The only case that could be a potential threat is if you drove into an extremely deep puddle, submerging the intake head. The car would have to be in the water so that the intake was submerged, and then it would start sucking up water, making your engine hydro-lock.
In both cases the intake is collecting air from outside your engine compartment. The purpose of the intake is to collect a colder air charge than inside the engine compartment, allowing the fuel management system to give the engine a denser air/fuel charge into the combustion chamber. To clarify: Cold Air = More Horsepower. The warm air from your engine compartment is good for fuel economy, but because is has less oxygen molecules than a cold air charge, the fuel will be leaned out. This increases your fuel efficiency, but decreases your horsepower. To conclude, you should look at your car and figure out what system will work with your car's ground clearance and hood type.