hugo/docs/content/en/functions/collections/SymDiff.md

title	description	categories	keywords	action	related	aliases
collections.SymDiff	Returns the symmetric difference of two collections.			aliases returnType signatures symdiff any COLLECTION | collections.SymDiff COLLECTION	collections.Complement collections.Intersect collections.SymDiff collections.Union	/functions/symdiff

Example:

{{ slice 1 2 3 | symdiff (slice 3 4) }} → [1 2 4]

Also see https://en.wikipedia.org/wiki/Symmetric_difference.