Chi

You should start by reading my article on the various types of qi. Here you will see that what many refer to simply as Qi is actually a combination of multiple types of Qi including what we eat, the nourishment from the air, etc. Ultimately there are many levels to Qi and you should explore them with qigong and/or tai chi so that you have some first hand experience of what the ancients are speaking of. There are some good introductory texts within my section that may be helpful.

It is also important to not confuse the ayurvedic system of air with the Five Elements of Chinese Medicine.

There are many systems which are complete in and of themselves but they don't need to meet at every point to end up at the same result. When you work with the philosophical constructs of Chinese Medicine you need to be fairly precise in what exactly you are wanting to know. Comparing systems is generally a waste of effort, particularly when compared to fully understanding one and taking the time to find out where it leads you.