The partnership in guilt is that they are involved in killing so many (innocent) people to take the throne.
As for the difference in character and outlook, perhaps the easiest example of this comes from the very start of Act I, scene 5. There you see Macbeth's gentler nature and more hesitant approach to life in how he phrases things in his letter. You also see his wife's firmer/harsher/more focused nature in her response—and that she is aware of it. He's not sure what to do; she says she'll need to pour her spirits in his ear to get him to do what needs to be done.