I am still single so I really can't differentiate it. But based in what I have observed, when someone gets married to a spouse, their priority suddenly changes. Before when they were still single, they would do whatever they want, go to wherever they like and buy what they desire for themselves. But if you are married, you should your spouse as your first priority before yourself and eventually your kids as well before your own good.
I think there are lots of difference in married and single life. It would be very hard to even imagine those changes especially to a single person, who have lived most of his life, virtually for himself without actually thinking of another person similar to how he should think and take care of himself. I think one of the biggest adjustment is the money aspect, once you become married, your money is not your own anymore. I mean, you have to allocate it in the proper department of your married life like savings, housing, daily expenses, and the fact that you have to save either for your family or the idea of building one. Another one is your routine, it would surely change because your cannot live like you no one is relying on you, once you have a spouse, more so a family, that would certainly change.