"differ in amount" is correct and usable in written English
You can use it to describe situations in which the quantity of something varies between two or more groups or things. For example: "The amount of rainfall in different parts of the country can differ in amount."
The examples given in this paper show that correlation coefficients calculated at individual level (future teachers) differ in amount and meaning from those calculated at program level or computed separately for different program-groups.
The two programs differ in amount of classroom hours (180 to 360 hours), number of examinations (2 orals and 2 written to 1 written), and additional requirements, such as scientific papers/presentations and participation in practice-based research networks.
In another study these authors found that selenium, although being generally low in Icelandic forage, did not differ in amount between forage samples from scrapie-free, scrapie-prone or scrapie-afflicted farms [ 7].
Since very young males have been shown to considerably differ in amount and composition of the pheromone [ 42] males were all caught at an age of 12 17 days and kept in small polystyrol vials (height: 80 mm; diameter: 35 mm) with moist sand and a drop of honey for two days to allow the pheromone glands to be replenished.
Although the number of twin pairs who differed in amount of formal education was small, it was still the case that having a lower education than one's twin partner was associated with approximately doubling risk of Alzheimer's disease (Gatz et al. 2001).
Meals A/B and C/D not only differed in amounts of calories and lipids but also in consistency because meals A and B were liquid and meals C and D solid.
Census records for different years differ in the amount of information.
Beef cattle with different feed efficiency substantially differ in the amount of feed consumed to achieve the same productive performance [ 8, 28].
However, in heterogeneous networks, there are different types of nodes who mainly differ in the amount of computational resource built inside them.
Although the two RUSFs did not differ in the amount consumed, there was a significant difference in consumption between chickpea-based RUSF and Pushti packet (p = 0.012).
At the point of maximum microbial N accumulation, Tryp and Ur did not differ in the amount of glucose C used (29.4 and 28.9 mg), but did differ in the amounts of cell C (10.1 and 6.0 mg), organic acid C (17.4 and 13.8 mg), glycogen C (3.81 and 6.07 mg), and total microbial product C (35.4 and 29.6 mg) present.
