We then have the fact that Hela herself was probably not at full power yet as the longer she was on Asgard she was still drawing her power from it. Hela from the comics has more feats. Hela Comics Hela vs Surtur MCU is clear. She blocks multiple attacks from comics Kurse who has limitless strength and binds him She also bests Thor from the comics in combat and severely injures him.

She is able to easily bust through a stone wall which 16,700 tonnes of force is necessary to do so.

first fight - Surtur from the beginning of the movie and Hela VS Doomsday at its best.

Thor was fighting a weakened and injured Surtur whereas Hela was fighting Surtur reunited with the Eternal Flame and at planet killing size/power. Before Odin trapped him, he had been powerful enough to destroy all of Asgard by himself if he wanted, so once he's restored, Hela is no match for him. So Thor is fighting Surtur at only a fraction of his true power, while Hela is fighting him after he's been reunited with his Eternal Flame, and is at his full power. Hela solos.