Power Drill vs Impact Driver

So hopefully at this point in your life you're at least familiar with what a Power Drill is. I assume this because, well, you can read. Drills are such a staple to the trades, we tend to be introduced to them pretty young. But what about Impact drivers? They're relatively new to the market (compared to Power Dills) and seem to be the same as a drill, at first glance.
They are not the same thing and with the combination you can get any job done. The proper use of a drill is drilling. Sounds obvious, but we have to get that out of the way. Some drills have hammer settings (see[Hammer Drill]), others just speeds. We'll define drilling as - boring a whole. Using different [Drill Bits], Power Drills can make all types of holes for all kinds of tasks.
Then there is the Impact Driver. This is not to be confused with Impact Driver Sets. which are basically the hand tool version. The driver has a device in it to make screwing in, or driving, screws easier and allow you to have more control. To understand the Electric Impact Driver you need to understand the impact mechanism itself. I'm going to keep this really basic. When force is encountered by the motor, it applies "hits" of rotational force on the shaft. This little "hits" will help move stuck screws or bolts. Once you use an Impact Driver, you'll realize how essential they are. Some people also like to use Impact Drivers when using paddle bits. I prefer to do all my drilling with a drill.
They are not the same thing and with the combination you can get any job done. The proper use of a drill is drilling. Sounds obvious, but we have to get that out of the way. Some drills have hammer settings (see[Hammer Drill]), others just speeds. We'll define drilling as - boring a whole. Using different [Drill Bits], Power Drills can make all types of holes for all kinds of tasks.
Then there is the Impact Driver. This is not to be confused with Impact Driver Sets. which are basically the hand tool version. The driver has a device in it to make screwing in, or driving, screws easier and allow you to have more control. To understand the Electric Impact Driver you need to understand the impact mechanism itself. I'm going to keep this really basic. When force is encountered by the motor, it applies "hits" of rotational force on the shaft. This little "hits" will help move stuck screws or bolts. Once you use an Impact Driver, you'll realize how essential they are. Some people also like to use Impact Drivers when using paddle bits. I prefer to do all my drilling with a drill.
Chucks
The major difference, besides the use, you need to take note of is the "chuck." The chuck is the opening at the tip of the drill/driver. This opening is what holds your bit. On a drill you will see three "teeth" that come out and grab the bit. As much as possible, line these up to the flat sides of your drill bit for the best grip. Yes there is a little indent, but that's for round bits not corners. This chuck is very versatile and can hold any shape bit that fits inside.
On the driver the chuck is very different. It's usually a 1/4" hex chuck. It's simply a 6 sided hole, that will hold a corresponding bit. These bits have to be exactly the right size and shape to fit. This is the standard size for drill tips anyway. There are sets of bits and tips specifically for Impact Drivers. You'll notice when you push in your bit it clips into position. And to remove you, usually, just pull the chuck away from the driver and it just pops right out.
On the driver the chuck is very different. It's usually a 1/4" hex chuck. It's simply a 6 sided hole, that will hold a corresponding bit. These bits have to be exactly the right size and shape to fit. This is the standard size for drill tips anyway. There are sets of bits and tips specifically for Impact Drivers. You'll notice when you push in your bit it clips into position. And to remove you, usually, just pull the chuck away from the driver and it just pops right out.
On a Budget
So you may be thinking at this point, "which one will more easily do the job of both?" In all honesty, you can get away with just one. I recommend getting a driver over a drill in this situation. They make drill bits that specifically are for drivers, they fit in the hex chuck and are made of material that can resist the impacts. I say the Driver because for most amateurs, you wont need to pre-drill everything you do. You also wont be working for eight hours a day, and just be wasting time, switching your bit back and forth. Now lets say you were [redecking] your old deck. Well you'll want to pre-drill all your screws and, depending on the size of your deck, you'll want the combination set. Also remember the combo comes with a hard or soft case, a charger, and battery(s). They're also, usually, about the same as the two bare tools.
Tool Basics
Tool Basics