What is the difference between absolute and difference threshold?

[Deepak]

The absolute threshold is the minimum amount of stimulus required for detection, like the faintest sound we can hear. The difference threshold refers to the smallest difference between two stimuli that can be detected, such as noticing a slight change in volume.

 

[BarryRaymo]

The absolute threshold is the minimum amount of stimulation needed for a person to detect a stimulus 50% of the time (e.g., the faintest sound you can hear).

The difference threshold (or just noticeable difference) is the smallest change in a stimulus that can be detected 50% of the time (e.g., noticing a slight increase in volume).