This is an interesting question, especially as it is complicated by the fact that most of our information about the older Catherine Linton comes from Nelly Dean, a classic unreliable source.
If we trust Nelly's account, the older Catherine was much more aggressive, self-centered, selfish, and self-willed than the younger Cathy. Nelly paints the older Catherine as manipulative, cruel, and bullying. The younger Cathy is more of an angel, sweeter and kinder in Nelly's telling, though we must note that this younger Cathy is quite rude and callous towards Lockwood when she meets him, as well as towards all the other inhabitants of Wuthering Heights.
While the older Catherine was undoubtedly a fierce, strong, and aggressive young woman, Nelly has every reason to magnify those characteristics and twist them to look as bad as possible. This is because Nelly's own actions are implicated in Catherine's grief and ultimate death. First, Nelly doesn't alert Catherine to Heathcliff's having overheard her remarks about not being able to marry someone as degraded as he. Nelly is angry at Catherine for pinching her and being high-handed and wants Heathcliff to overhear wounding words from her that sound cruel and calculating.
Later, Nelly is aggravated at Catherine and won't tell Edgar how sick she is, thinking that she is faking it to get attention and to bend everyone to her will. If she had let Edgar know sooner, he might have been able to save Catherine's life.
To justify her own behavior, Nelly has to paint the older Catherine as an unlikable, demanding person who brought trouble onto herself. While we don't know for sure, it is probable that the two Catherines, mother and daughter, are actually very much alike. Heathcliff sees a very strong resemblance between them. The older Catherine is likely less of a demon and the younger less of an angel than in Nelly's version of the story. Both are strong-willed people who have suffered abuse in dysfunctional homes.