Language Branch: A language branch is a smaller division within a language family. It consists of languages that are more closely related to each other than to those in other branches.
Proto-language: Proto-language refers to the hypothetical reconstructed ancestral language from which all languages within a particular language family originated.
Language Group: A language group is an even smaller division within a language branch. It includes languages that share similarities but are not as closely related as those within the same branch.