[gervu]

Between Elixir and Erlang, there's no difference because it's all BEAM bytecode when it runs.

Between arbitrary individual functions you might encounter, there can be differences, but only in the sense that it could happen between Erlang and Erlang if the functions had different implementations or degrees of optimization or optimization choices.

Worth noting for prospective adopters is that you can seamlessly call Erlang functions from Elixir by adding a : prefix, such as :random.uniform(), and there's no weird overhead or surprises involved.