Four Modes of Consiousness

It is one consciousness which functions in four different ways:

The mind which performs the perceiving function of the consciousness.
Judging, discriminating, enquiring, agreeing, disagreeing, etc., which is called the intellect is the second mode of consciousness.
Memory which is involved with storing that which has been perceived.
Identifying with what has been perceived is the fourth mode of consciousness which is called the ego.

Therefore manah (mind), buddhi (intellect), chitta (memory) and ahankar (ego) are the four different functions of consciousness.