Key Difference: Sensations are things in our environment that are registered by the five major sensory organs. Sensation is what we see, hear, smell, taste and feel. Perception is how we interpret these sensations. Perception helps us make sense of our sensations.

The words ‘sensation’ and ‘perception’ are interrelated, which makes it quite easy to mix up the definition of the two words. Sensation is essentially the ‘feeling’ what we feel with our senses. Sensations are things in our environment that are registered by the five major sensory organs. Sensation is what we see, hear, smell, taste and feel. Perception is how we interpret these sensations. Perception helps us make sense of our sensations.

Dictionary.com defines ‘sensation’ as:

• The operation or function of the senses; perception or awareness of stimuli through the senses.
• A mental condition or physical feeling resulting from stimulation of a sense organ or from internal bodily change, as cold or pain.
• Physiology. The faculty of perception of stimuli.
• A general feeling not directly attributable to any given stimulus, as discomfort, anxiety, or doubt.
• A mental feeling, especially a state of excited feeling.
• A state of excited feeling or interest caused among a number of persons or throughout a community, as by some rumor or occurrence.
• A cause of such feeling or interest: The new Brazilian movie was the sensation of the film festival.

Dictionary.com defines ‘perception’ as:

• The act or faculty of apprehending by means of the senses or of the mind; cognition; understanding.
• Immediate or intuitive recognition or appreciation, as of moral, psychological, or aesthetic qualities; insight; intuition; discernment: an artist of rare perception.
• The result or product of perceiving, as distinguished from the act of perceiving; percept.
• Psychology. A single unified awareness derived from sensory processes while a stimulus is present.

The main difference between sensation and perception is that sensations are the passive process of bringing information from the outside world into the body and to the brain. Perception, on the other hand, is the active process of selecting, organizing, and interpreting the information brought to the brain by the senses.

Sensations are passive, in the sense that we do not have to be consciously engaging in a "sensing" process. It is what our senses do naturally and at all the time. However, perception is what our brain actively does: it interprets the sensations.

Sensation is the process by which our senses gather information and send it to the brain. Humans are capable of sensing a large amount of information as any given time, such as room temperature, brightness of the lights, someone talking, a distant train, or the smell of perfume.  However, due to too much information, our brain does not interpret everything.

For example, if you are talking to someone, you might not realize that someone just walked in the room, even though you probably did hear the door creak and their footsteps. It’s just that your brain didn’t interpret the information, and hence you didn’t perceive the person walking in. Due to this most of our world goes unperceived by us. Scientists estimate that we observe 11,000,000 bits of info per second. However, we interpret only 40 bits.

Also, perception can be shaped by learning, memory and expectation. An example of this and an easy way to distinguish between sensation and perception is that: When we see a building from far, it appears small. When we walk towards the building it appears to get bigger, at least that is what our eyes see. However, we do not exclaim in surprise that the building is growing, or that we are shrinking. It is because we know that the building is the same size as it always was, as we are as well, it’s just our relative distance from the building that makes the building appear so.

Another example of perception shaped by learning, memory and expectation is when we walk into a room. If anything is amiss, or if something has been moved or removed entirely, we can tell the difference. Our eyes see the room, and we perceive that something is different from before.

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