You are currently playing on the map caen (also known as camp fest 2013). You are an axis covert ops and you are supporting the engineers to escort the tank while keeping them safe from the hoards of allies that are camping close to their spawn, which is also close to your objective (the office wall).
The engies ask you to throw poison gas at the tank to "help" them while they try to repair the tank.Their plan will fail very quickly and they will insist you to keep doing the same thing , they will give even get mad at you for not setting them on time.
Don't worry , it's not your fault. It's just their dumb plan and lack of knowledge of the game's gameplay mechanics.Just because you have to earn XP to unlock poison grenade it doesn't means that it's better.
I am here to explain the differences between them so you can shut all those annoying kid's mouth ,that are constantly telling you what to do and getting mad because you have common sense and did the correct usage of these sexy items.
First let's see the test 1: The visual aspect (I reccomend to zoom the images for better detail appreciation)
Now let's look at test 2, I asked an Axis soldier to stand still on Venice's mortar alley(naabish volunteered to help me out on this one).
Now that you know the visual differences , let's talk more about the poison gas grenade.
It takes approximately 6 seconds to kill a fully healed enemy soldier with one poison grenade.
It takes approximately 4 seconds to kill a fully healed enemy soldier with two poison grenades.
How to use poison gas correctly:
You are on Makarech streets (the night version) and you are an allied covert ops, took some pants from the enemy and you are helping your teammates by dealing incoming enemies and opening door.
Now let's get more complex by combining gas grenade and satchel.
How to use smoke grenades properly
Only use them for STEALTH
Use them when you are escorting a tank to help your teammates to avoid getting killed by rambo medics and snipers.
Use them to capture a flag (also known as "They captured the forward bunker) throw the grenade close to the flag to provide a safe position for you teammates while your enemy if confused trying to find the flag.
But you know what's even better?? USE BOTH!!!
If you use smoke and poison grenade one after another , you will create a death trap that will not only confuse your enemies, but also killing them. If they are on a small room camping or waiting to get through the door (makarech or goldrush gals for example) throw the nades using my examples above and you will grab them by the man spheres and they will bow to you as a covert ops master.
Remember that they have six seconds to find a medic or get out of the room unless they want to be dead.
and that's pretty much it , now it's your turn to apply these techniques and use them correctly for your and your TEAMMATES' advantage.