In such fanfiction, Yuuki might be depicted as more alluring and perhaps more assertive in her relationship with Zero. Zero, on the other hand, could be shown as more brooding and possessive. However, this is a very general view and can vary greatly depending on the author's interpretation.
The plot involves Rimuru's journey from being a rather weak (initially) slime to becoming a very powerful being. He meets many interesting characters. For example, there are the goblins he befriends early on. Rimuru helps them improve their living conditions. As the story progresses, he also has to deal with the threat of other more powerful monsters and even some human kingdoms that view his growing power with suspicion. In general, it's a story full of adventure, growth, and the forging of relationships in a magical and dangerous world.
Kirito is more of a traditional swordsman in terms of his combat style. He often relies on his sword - fighting skills and his ability to quickly analyze his opponents. Yuuki, on the other hand, has a very unique and flashy fighting style. Her movements are more acrobatic.
The main character is Rimuru Tempest. He is a slime who has unique powers and a great deal of charisma. Another important character is Veldora, the storm dragon who befriends Rimuru. There is also Shizu, a human who has an impact on Rimuru's early development. And then there are characters like Benimaru, a powerful ogre who becomes one of Rimuru's loyal followers.