To have everything in common wouldn't create a perfect match like Cancer and Pisces. They are different in the best possible way, because their differences complement each other. For example, Cancer is a known nurturer and caregiver, while Pisces seeks connections with others. These two qualities match up well, as Pisces is willing to be nurtured in order to make a connection with their Cancer.
Though these traits can bring them together, they can often cause a little conflict, too. Cancer's sensible, caregiving nature makes them financially rigid - they love having plenty of money in the bank so they can take care of their loved ones. Whereas Pisces is a bit more spontaneous with cash and loves spending it on socializing and fun. Remember, this is all about making and maintaining connections for them, so they consider it essential spending.