O'Sullivan & Hilliard's The Law of Contract (2018 8 ed). 16.23 starts on p. 387, 16.35 on p. 391.
Right: Pindyck, Rubinfeld. Microeconomics, Global Edition (2017 9 ed). p. 152.
Difference in value or cost of cure? (Section 11.3.1)
The £2,500 award made in Ruxley for Mr Forsyth’s ‘loss of amenity’ can be interpreted as damages for non-pecuniary loss, based on the fact that the contract was a consumer contract for enjoyment (see the opinions of Lords Clyde and Hutton in Farley v Skinner (2001)). However, the award may also be interpreted as a response to the need for a wider principle of recovery based on the loss of ‘consumer surplus’. Consumer surplus is the difference in value between what a thing is worth commercially and the higher value at which a consumer subjectively values it. So, whilst an extra few inches on the swimming pool added no financial value, the £2,500 represented Mr Forsyth’s consumer surplus: to him, and him alone, the pool was a more valuable asset if it was deeper (i.e. if his contract was fully performed). He had contracted for this extra depth and it had not been provided, so you could argue that the award of £2,500 was compensation for loss of this consumer surplus.
I'm not a microeconomist, but these terms appear to be defined wholly differently? Or am I overlooking something similar that underlies them?