The mind is often divided into two parts:
The analytical mindEdit
The part of the mind that thinks analytically, that is self-aware. In other words, it is the pc, the individual. Which makes this a distinction without a difference, which is confusing.
The term analytical mind was first used before LRH had separated out the thetan from the other parts of man, and is a holdover from those times. It is a misnomer, but convenient in explaining the subject to new people as it sidesteps the problem of introducing the concept of thetan to someone who might reject it.
The reactive mindEdit
The reactive mind is where data is stored when the analytical mind is unable to take in the data. This happens when a person is unconscious by reason of alcohol, injury, drugs or exhaustion. While a person is in this state, everything he or she hears, sees, touches etc. and any pain felt is recorded in the reactive mind as an engram.