What an interesting question!
I often compare my two and wonder who is smarter, because one is more stubborn and the other picks up tricks faster. I can't say who is smarter though, because they're both very intelligent in different ways. They also have different approaches to get the same things too.
Here's a short video of what they do when they're hungry and want their dinner lol:
https://www.instagram.com/p/BO8ZvJph...cottieandcasie
I think I attribute their differences to personalities, rather than level of intelligence.