Flight: Stormbreaker allows its user to fly through the air without to spin it like Mjølnir. Healing: The axe was able to fully heal Thor and restore his strength when he was badly burned exposing himself to the power of the dying star.
Both weapons can be summoned by Thor, and will return to his hand after being thrown. Both weapons also enable Thor to fly, and to channel his power to summon lightning. Stormbreaker has the additional power to summon the Bifröst, allowing Thor to teleport anywhere in the Nine Realms.
Stormbreaker All Lightning/Thunder Power Scenes | MCU Compilation [Open Matte/IMAX HD]
Why can Thanos lift Thor's Stormbreaker?
Storm breaker is meant to be the strongest weapon of Asgard and could even summon bifrost, says Eitri. But there is no enchantment or spell on it like it was on Mjolnir. So one doesn't have to be worthy to weild it, just the strength to lift it. Clearly Thanos is capable of lifting it.
While no one besides Thor has been able to truly wield the awesome might of Stormbreaker, Groot was the very first being to hold this weapon when one of his arms became the handle for the mighty axe.
Unlike Mjølnir, however, the weapon is not enchanted to prevent those deemed "unworthy" from holding it, making anybody with sufficient strength capable of using the weapon.
Why does Thor like Mjolnir more than Stormbreaker?
It may be weaker than Stormbreaker in the Marvel Cinematic Universe's lore, but Mjolnir carries the bigger legacy since it holds a deeper meaning to Thor and anyone was worthy enough to wield its power.
By most accounts, Superman seemingly outclasses Thor in terms of raw strength, especially in earlier versions of the DC Universe. He's pulled planets, punched people into orbit, and performed all sorts of wild feats of strength.
On their own, both these noble heroes are capable of beating incredible forces. But for all Shazam's power, he does not match Thor's experience in using the more arcane elements of his abilities.
Only Thor can produce lightning without Mjolnir. But the point of carrying Mjolnir means whoever carried it are worthy to be the king of Asgard and gets the power of the God of Thunder. But if someone wields the hammer and if Thor is still worthy of wielding the hammer, than the 'someone' couldnt produce lightning.
Many viewers have pointed out that Thanos was able to lift Stormbreaker without a problem, but this is because the ax isn't enchanted as Mjolnir is. Others believe Thanos lifted Mjolnir (although briefly) and have even argued that he would be worthy of doing so.
Although Stormbreaker and Mjolnir have very similar properties and powers, Stormbreaker is the most powerful weapon wielded by Thor so far. The obvious reasons are that Stormbreaker is the physically larger weapon out of the two, and not to mention that it is an axe, which could well be more dangerous than a hammer.
If Thor decides to use the power of lightning onboard the Asgardian refugee ship to fight the villain and his minions, he may accidentally damage the ship, or worse, even kill his own people. So, he chose to hold himself back, allowing some Asgardians to escape with Valkyrie (Tessa Thompson) and Korg (Taika Waititi).
The most likely reason is when Groot's arm was separated from him, it became a part of the full weapon and was enchanted to be virtually indestructible. Stormbreaker is a weapon of Nidavellir, which are magical, so it's entirely possible.
Mjolnir has the enchantment where only those who are worthy can wield it, such as Thor or Captain America. Hulk on the other hand, … while Stormbreaker can be wielded by anyone who has the strength to do so (though it can be summoned by those worthy of Mjolnir like Cap did). Case in point, Thanos.
Gorr the God Butcher possesses enhanced strength, durability, and agility due to his alien physiology and absorption of divine energy. Stormbreaker, a powerful enchanted weapon forged by Eitri, allows beings of sufficient strength, like Gorr, to wield it.
In the MCU, Stormbreaker was forged by Eitri at the behest of Thor, as a weapon to use against Thanos and his Infinity Gauntlet. In the comics, however, Stormbreaker was still made by Eitri, but pretty much everything else is different.
It's important to note that the rules around worthiness had been temporarily suspended to allow this to happen. As soon as the fight was over, Superman couldn't lift the hammer anymore. However, under normal circumstances, without any weird interference, Superman is worthy of Mjolnir.
Without the Infinity Gauntlet, Thanos stands little chance against Prime Odin. Odin is stated to be able to shatter the Earth. And he turned Frigga into stars. He has devastated while worlds, laid waste to kingdoms and destroyed demons and monsters.
Mjolnir is not particularly heavy, it weighs 42.3 lbs. The fact that almost no one except Thor can lift the hammer has nothing to do with it's physical weight. The hammer is enchanted so that only those deemed 'worthy' are able to wield it.
