Sure, lets compare Ainz and Rou (the MC of Re:M):
Background: Ainz is an average joe salesman who spends his free time gaming explaining why he have a lot of knowledge about game mechanics. Rou by contrast is an elite super soldier who spends his free time dating women, and yet when he comes into a world based on game mechanics he instantly understands how to take advantage of this.
Relationships with subordinates: Ainz, for all his flaws, deeply cares about his subordinates, and yet is still paranoid about them potentially turning on him, which gives an interresting dynamic between them. Rou by contrast views most of his subordinates as disposable mooks, and the ones he doesn't he usually have a very one dimensional relationship with, which doesn't lend itself to interresting interactions.
Intelligence: Ainz is slightly above average and mostly dangerous due to having learned the game mechanics and tactics by heart. Rou by contrast have little experience gaming, yet adapts insanely quickly to any situation, deduces the proper countermeasures to any attack and takes them so fast that they don't have time to land, and easily outwits the strategies of trained militaries.
Sex: Ainz cannot have sex, even though Shalltear and Albedo are practically throwing themselves at him, which prevents the story from becoming a sex fantasy, also outside of Nazarick the only women who are attracted to him are those that don't know how ruthless he can be. Rou by contrast can have sex, and he have a lot of it, every woman he meets ends up falling in love with him, even those whom he have enslaved killed all their friends and loved ones right in front of, which makes no sense.
Supporting character: We see a lot of different POV in overlord and have a lot of interresting 3 dimensional characters with different reads of Ainz, some good some negatives, but most are hilariously wrong. In Re:Monster most really comes from Rou's point of view and most characters simply exists to think he is awesome and only people who are incompetent snobs think anything bad about him, and it is clear the narrative thinks those who view him badly are wrong... Even though it is clear that he is a rapist, torturer, enslaver and he attacks innocents unprovoked.