Glossary: Blood Choke and Air Choke

The difference between a blood choke and an air choke is a very important one: 

Blood chokes are chokes that cut off circulation to the brain. This is done by compressing the carotid arteries and therefore cutting off the supply of oxygen to your noggin (aka cerebral ischemia). Unconsciousness can occur in as little as three seconds. 

The two most common blood chokes are the read naked choke and the triangle choke. 

Air chokes are chokes that cut off air flow down the trachea. Air chokes typically rely on strength rather than technique for their effectiveness, as such they are typically not as efficient or effective in martial arts as blood chokes. Air chokes are also freakin' dangerous, as they can cause damage to your opponent. As such, many schools or competitions restrict the use of air chokes or ban them all together. 

The most famous example of an air choke is the Homer Simpson choke (sadly, more commonly and tastelessly known as the "rape choke"). 

It's important to note that while the reaction to a blood choke might be relatively innocuous ("OK, I've been here before, work my defense. Get out or tap....") the reaction to and air choke is typically much more violent and unpredictable ("holy shit, someone's trying to kill me...panic!"). 

Given that 1) air chokes tend to take longer to apply than blood chokes 2) air chokes require strength rather than technique and 3) air chokes are more likely to damage your partner it should be obvious that blood chokes are superior. 

One should also note that depending on a variety of factors, it's possible that a hastily applied blood choke could be an air choke. This most commonly occurs when you haven't put the choke on properly (say in a RNC) and your forearm is across your opponent's adam's apple rather than the side of his neck. 

If you find yourself in that situation, don't continue with the choke and risk hurting someone - give it up and try for another submission.