Exam definition for differential threshold?

[lovebusiness]

From the posts that i have read, someone said that they're teacher said you can't use " between two stimuli " . Sorry i can't seem to find the post anymore but i was wondering if on the exam we SHOULD use " between two stimuli " as part of our definition , OR not

These were solutions to short answer questions that i did in class and it said " between two stimuli " ( look below for  details, i attached the solution part to it) 

SECTION B: Short answer and extended response – suggested
solutions
Question 1
(a) Define the term “absolute threshold”. (1 mark)
• The minimum amount of physical energy (physical stimulation) that is
needed to detect the presence of a particular stimulus (a neural impulse to
fire).
(For vision: the lowest level of light illumination that the eye can detect, on
average, in 50% of trials.)
(b) Define the term “differential threshold”. (1mark)
• The smallest perceptible difference / change that can be detected
between two stimuli by a specific sensory receptor.

Thanks !!

[Visionz]

Im using:
Differential threshold - also known as Just-Noticeable-Difference (JND), is the smallest perceptual change able to be to be detected in a stimulus, on average 50% of the time.
That should show enough of an understanding.

For Absolute threshold:
Absolute threshold - the minimum amount of light energy necessary for a stimulus to be perceived, on average 50% of the time.

[akira88]

Or for the differential threshold you could say:
The minimum amount of light energy needed to detect a change in a stimulus 50% of the time.
Basically the same as Visionz' (or Visionz's?) definition

[Visionz]

Visionz'z'z