Sensation:Sensation is the process through which our sensory receptors detect and respond to stimuli from the environment.
Threshold:A threshold is a dividing line between what can be perceived or detected and what cannot. It represents the minimum amount of stimulation required for perception.
Difference Threshold:The difference threshold (also called just noticeable difference) is the smallest amount by which two stimuli must differ in order for an individual to perceive them as different.