I wonder what are the ways for measuring the degree of differences between two numbers on a given scale. For example, if two persons are asked to each choose a number between $0$ to $10$, how can we measure the degree of the difference between their choices (e.g. $3$ and $9$)?
A plausible way is to normalize the difference by the scale, so for the example above it would be $\frac{\left|3-9\right|}{10}$. Thus the maximum degree of difference here is $1$, whereas the minimum is $0$. Conversely, if we want to measure the level of similarity, we can do $1-\frac{\left|difference\right|}{scale}$ here.
Is there any other alternative/better way? Thanks.