The key difference between compressed air and CO2 is that the pressure of compressed air is much higher than the normal atmospheric pressure while we usually store carbon dioxide at low pressure.
The atmosphere consists of various gases and particles, which we need for various purposes. Oxygen is one of the most crucial things on the earth which determines the survival of living things. Other than that carbon dioxide is also important for the survival due to its importance in photosynthesis. Except for these natural phenomena, people developed methods to make use of air to fulfil their various needs.
