रक्षो-भेदः

Source: TW

The taittirIya shruti hints that the rakShas are a brother race of the yakSha-s. The rAmAyaNa confirms that.

The yakSha-s are generally beneficent especially when properly invoked.
The king of the yakSha-s receives shrauta rituals like the gods.

The rakSha-s are malignant in contrast and generally cause obstructions to shrauta rituals.
The rAmAyaNa has a second type of rakShas: a yakSha or a gandharva who due to a curse have become a rakShas.