Why should I use assert_equal instead of just assert with an equal operator in minitest?

I really enjoy Minitest and it's simplicity but I don't understand why I should use assert_equal instead of assert with the == operator.

If I look into the Implementation the assert_equal method does exactly the same as I said with the equal operator.

Why do I need this step in between and not just use it directly?

I also think that it won't be more readable just because of the equal there since == is pretty self explaining.