I don't think I sit down and consciously think about their similarities or differences, but I know it happens in the passing of days. My hubby, for example, hires work done around the house. Drives me nuts, because my dad used to do a lot of the work, and that was our thing to do together -- I was his go-fer' and flunky. I enjoyed it with Dad, and would like to have that experience with the hubby, but he just cannot wrap his mind around the thought of doing things of that importance that he's never done before. And, now that we're getting older, I guess it's a moot point!
There are also a lot of similarities between them, which feels comfortable and right. I can't imagine being maried to someone that didn't have at least some of my dad's qualities.