Function diff 

pub fn diff(a: &Version, b: &Version) -> Option<Difference>

The release-type difference between a and b, or None if they compare equal.

The result is symmetric (diff(a, b) == diff(b, a)) and, like semver comparison, ignores build metadata. Mirrors node-semver’s diff.

use semver::Version;
use semver_diff::{diff, Difference};
assert_eq!(diff(&Version::new(1, 0, 0), &Version::new(1, 1, 0)), Some(Difference::Minor));