The main difference you’ll find is that an AEG performs better, and the GBBR is more realistic.
On the market, you can find hundreds if not thousands of replicas. Differences range from each other in materials, weights, configuration, performance, and more.
One of the most important variables, when you are considering the purchase of an airsoft rifle, is the operating system. Generally, you have a choice between electric-powered, as in the case of Airsoft Electric Guns (AEG), or gas-powered, such as Gas BlowBack Rifles (GBBR).
Both systems offer several advantages and disadvantages: let’s take a look at them together:
Yes, we are aware of HPA (High-Pressure Air) airsoft guns, but that’s for a different article.

Differences between AEG & GBBR
The biggest difference between the two systems is, of course, the operating mechanism.
AEGs feature electrical and mechanical components, driven by a motor powered by a battery. By pulling the trigger, the mechanism is activated, causing the gears to spin. This spin pulls on a piston, which upon release, ejects the BB.
Next, the hop-up sets a backspin on the BB that influences its trajectory and range of the shot. Electric replicas tend to be very stable, as there is no recoil typical of gas-fired replicas.

However, some brands have released on the market some AEGs equipped with a battery-powered blowback mechanism, whose purpose is to simulate the recoil of a real firearm, increasing the realism of the replica.

In the GBBR system, however, the operation is purely mechanical, as the pressure is released through a system of valves placed inside the replica, and provides not only the ejection of the BB, but also to set in motion the reloading cycle of the weapon, as would happen in a real rifle.
In fact, most of these replicas have a realistic shooting cycle, which makes the whole bolt move, increasing the realistic look of the replica.
Most GGBRs also have a hop-up, which performs the same function as AEGs. However, be careful if you think about replacing it. You will need to find a specific hop-up designed for GBBR as the buckings and hopup systems are typically different between an AEG vs GBBR.
Moreover, in this kind of system, it’s possible to enjoy some kind of recoil. The pressure vents of the GBBR create a movement that resembles the movement caused by the recoil of a firearm.

Externally, you’ll find that there are very few differences between a GBBR & AEG with one factor: if it has a plastic body, it is probably an AEG.
Pros & Cons of the AEG
Pros & Cons of the GBBR

Choose an AEG for Performance
So, to recap, the essential reason for choosing an AEG is to look for the best performance. The stability resulting from the lack of recoil makes them extremely easy to swing and shoot. In addition, the mechanisms that allow an AEG to function allow for reliable full automatic.
It is very easy to solve any operational problems related to a discharged battery since they are tiny and easy to carry and replace, even in emergency situations. It’s a good idea to have a couple of spare batteries with you, in case one runs out.
Make sure you carry a battery suitable for your replica, so as not to strain the mechanics. Shooting with this type of replica will not give too much satisfaction between your hands, but it certainly pays off when you see the shots reach the target.
The absence of recoil allows you to stay accurate even when shooting at very distant targets. This would be way more difficult to do with a GBBR, whose movements can strongly affect this type of shot, especially in full auto.
Speaking of full auto, thanks to the electrical components it is possible to obtain very high ROF. With a high-quality electronic trigger & airsoft mosfet, it will further increase the performance while shooting.
In addition, it is important to pay attention to the humidity of the playing area. High humidity percentages may result in a negative impact on the functioning of AEGs. They sometimes cause premature discharge during a trigger squeeze.
As a general rule, an AEG should be your weapon of choice if your goal is to perform outstandingly during firefights.
Many of the best airsoft brands on the market today focus their product design on performance. Generally, electric high-end products will probably beat most GBBRs in steadiness and precision, especially for shots beyond 150 feet.
Check out best airsoft M4 round-up. Spoiler: the best airsoft M4 is an AEG (in our humble opinion).
If it is realism you’re looking for, go for a GBBR instead.

Choose a GBBR for Realism
If your priority when playing is the pursuit of realism, there’s no doubt about it: the GBBR should definitely be your pick.
It’s the closest thing to a real weapon in almost every way: they have a functioning bolt, they recoil, they have a working bolt catch, and they stop firing once they’re out of rounds.
Even the trigger behaves like that of a real weapon: usually, it is mechanical, and allows for more realistic use than the electronic trigger on the AEGs.
Indeed, they are replicas that can give you something more if you want to take part in MILSIM events and will allow you to experience more concretely some “tricky” aspects of combat under stress.

For some people, having to manage the recoil of the weapon during a firefight may simply look like a handicap. However, for those looking to join simulation events, it’s an opportunity to experience something that it’s common with real firearms.
The most important thing is to prepare the replica and the magazines carefully before starting the airsoft game. You don’t want to have to carry bulky gas tanks or reload the magazines while in the middle airsoft combat.
Another thing to pay attention to is temperatures. Gas strongly influences the behavior of the weapon and the effectiveness of your BBs depending on the temperature. Typically, temperatures above 60 degrees are okay for gas recoil guns. 80 to 90 degrees is better.
Below is a video by Airsoft GI Boaz going over some of the more common reasons airsoft players might choose a GBBR. Additionally, here’s another video
Final Thoughts
As a final tip, I recommend as always, a pre-purchase study phase.
Figure out what your priorities are. What is your budget? What are the reasons why you are buying your particular airsoft gun.
If possible, try a few models of AEG and GBBR before buying yours, so you get an idea of how they work and how they are different.
Finally, discuss the topic with other players. Look for reviews on blogs and on Youtube to be guided in your purchase. Even reddit can be a decent source of information. The world of airsoft is vast and wide-ranging. A helping hand while searching can make the difference between a good and a bad purchase.
Stay safe, and have fun!