Maiar were lesser spirits who were formed to assist the Valar. Both Sauron and Gandalf (along with the rest of the wizards) were Maiar. Sauron served Aulë, who was the smith of the Valar, and learned from his skills that would later help him while forging the One Ring.
Sauron was a highly gifted Maia, originally an apprentice of Aulë, who became skilled at crafting and making. Coveting the power through which he would coordinate all things according to his own will, he joined with Melkor.
Sauron isn't stronger than them in any way whatsoever. The most powerful Vala is Melkor (Morgoth), even after losing a significant portion of his power. It took all the Valar to come to Middle-earth only to subdue Morgoth!
Sauron and Gandalf were both Maiar: a supernatural race that serve the Valar, and many Maiar assumed different forms. Gandalf is one of five Wizards, a group of Maiar originally sent to Middle-earth by the Valar to aid the resistance against Sauron, and were given the appearance of old men.
Sauron was originally a shape-shifting fallen angel and could take on various forms, including a vampire and a werewolf. Sauron's final form was terrifying and demonic, reflecting his own hate and evil, and he did not wear armor in the books.
Why Was Sauron so Powerful? (Even Among Maiar) - Middle-earth Explained
What was Sauron before he was evil?
Sauron was the most powerful of the Maiar—primordial spirits created to help the Valar first shape the World. His original name was Mairon, which means "the Admirable," and as an immortal spirit born before the world's creation, he was able to perceive the Creator Eru Ilúvatar directly.
Morgoth is the more powerful of the two. Morgoth was the mightiest of the Valar, a group whose weakest member would outpace Sauron. However, there are some circumstances and eras in which Sauron would win the day. Morgoth was born far beyond Sauron but lost and surrendered much of his power.
Bloodlines are very important in Tolkien's stories, and it makes a lot of sense that Sauron would fear the great-grandson of the man who cut off his hand. Aragorn carried the blood of Numenor with him. His genetic connection to the heroes of the Second Age established him as a dangerous opponent of Sauron.
"So I think in his pitch to Galadriel, it cannot mean that he loves her or that there's any kind of romantic relationship. There should be no ambiguity around the fact that Sauron is evil — he's terrible, and he's using Galadriel to enhance his power."
Additionally, while he was in his weakened state, Galadriel could hold him off through the power of will alone. However, if Sauron had his One Ring and faced off in a battle against Galadriel, it's unlikely that there would be much she could do.
Morgoth, the first to reign terror upon Middle-earth, was more powerful than Sauron and commanded an army of dragons and Balrogs. While both Morgoth and Sauron were cunning, Morgoth's rule and terror lasted longer and his corruption spread further, making him more formidable in the Lord of the Rings universe.
Finally Sauron came out to fight Elendil and Gil-galad face to face. When Elendil fell, his sword Narsil broke beneath him. Isildur took up the hilt-shard of Narsil and cut the One Ring from Sauron's hand, vanquishing Sauron.
Though wizards are technically Maiar, they do not possess all the same abilities in their wizard forms. This is why, despite Balrogs and Sauron also being Maiar, Gandalf wasn't evenly matched in his wizarding form—especially as Gandalf the Grey.
The majority of her powers come from her Ring of Power, Nenya, the Ring of Water. The ring, also known by the names the White Ring and the Ring of Adamant, is one of the three Rings of Power given to the Elves of Middle-earth in the Second Age.
Melkor is the most powerful of the Valar but he turns to darkness and is renamed Morgoth, the primary antagonist of Arda. All evil in the world of Middle-earth ultimately stems from him. One of the Maiar of Aulë betrays his kind and becomes Morgoth's principal lieutenant and successor, Sauron.
It was said that Morgoth hated and feared the House of Fingolfin most among the Houses of the sons of Finwë, especially Fingolfin's son Turgon, as it was prophesied that his doom would come from the House of Turgon.
Envy: He hates how he cannot make life and is jealous of Eru's ability to create life which is why he creates Discord and is the prime motivation of Morgoth. If it isn't mine, then I will destroy it. Gluttony: He breaks his promise and betrays Ungoliant, so he can keep the Silmarils for himself.
In his notes, Tolkien remarks that Sauron saw Galadriel as his equal. Add that to the fact that she's untrusting of Sauron (yes, even when he's in his Annatar guise) and an unwavering, single-minded force, and it's more likely than not that Sauron feared Galadriel — or the potential she held to upend his plans.
Vickers' comments imply that Sauron's intentions with Galadriel were primarily political in his dealings with the elves and that he was using her to elevate his power as a ruler over middle earth.
The first Dark Lord was the rebel Vala first known as Melkor and then as Morgoth. Denied the demiurgic power he desired, he was consumed by a nihilistic purpose: the destruction of Middle-earth. The second Dark Lord was Morgoth's successor, the subversive Maia named Mairon, and later Sauron.
Secondly, Balrogs were the epitome of malice and power while Sauron only ever won one of three fights he ever had. Sauron was the great deceiver. His power lies in planning, subterfuge, manipulation, and corruption.
This Gandalf defeated Saruman, so he is also above Saruman. However, he is still les powerful then Sauron. But, there are other beings in Middle-Earth at that time (Third Age). For example, Galadriel and Elrond.
