The Angels are considered one of the strongest races as of Dragon Ball Super, even teaching the Gods of Destruction how to control their powers. They also cannot die unless they violate one of the Angelic laws, to which they cease to exist if they do. Angels can naturally use the Ultra Instinct state, and have the ability to perform a Temporal Do-Over. Similar to the Kais, Angels also have the power of creation. They can resurrect anyone who has died -- unless they were killed by a Demon. It's heavily implied that the Angels are one of if not the most powerful race in creation. The only thing that truly limits them are the Angel laws.
Between the Saiyans, the Angels, and the Core People, it's amazing there's still a universe to call home. But one powerful, yet still mysterious race is the Demon Realm Race. Could they potentially be even stronger than the Angels?
Of course where there are Angels, there are usually Demons, and the Dragon Ball universe is no exception. While we've seen plenty of what the Angels can do, the same can't be said for the Demon Realm Race. They've mostly made appearances in the video games and the Super Dragon Ball Heroes manga, while only Dabura has appeared in the series proper. We've seen Demons, Devils, Majin, and Ogres throughout the series since the beginning, but the Demon Realm Race has remained rather elusive otherwise.
From what we've seen in the games, the DRR are rather adept in the use of magic. Like several other Dragon Ball races, they are able to transform, with their particular transformation resulting in a Dark Form. However, the only known user of this form is Dabura's sister Towa, who was able to become a Demon Goddess after gaining the powers from Mechikabura. Another member of the DRR, Demigra, also became a Demon God, but went even further to become a Transcended Demon God. The highest rank that can be achieved in the Demon Realm is Dark King. Dark King Mechikabura was able to use space-time energy to ascend beyond his perfect Demon God state.
With all of that power, one would think the Demon Realm Race would be on par with the Angels, but amazingly, they're most likely more akin to the Kais. This is because both the DRR and the Kais are part of the Core People Race. While there hasn't been any official confirmation in Dragon Ball that they are considered Core People, it's heavily implied. The Core People are born from the fruit of the Kaiju trees on the Core World home planet. A Kai is created in two ways: either they are born from a special golden fruit, or they are lucky enough to picked for the position through drawing lots. In the meantime, they study at a Hogwarts-esque castle-school.
However, an evil Core Person is born every once in a while. In this case, they are sent to live in the Demon Realm away from other races and are ruled by the Demon Supreme Kai. While it is possible for good Core People to later become evil -- such as the case with Zamasu -- it appears that those who are just born evil are automatically isolated from those who were born good and sent away without a second thought. Further evidence that the DRR are Core People is the fact that Demigra wears the green Potara earrings that are exclusive to Supreme Kais. So while the Demons are powerful, it appears they don't quite reach the status of Whis and the Angels.