Push notifications, email, and SMS can reach consumers in highly personalized ways, and all three behave and perform similarly to meet the goals of marketing campaigns. Perhaps for that reason, those three channels are sometimes thought of as interchangeable.
But that's likely not the case.
All three channels have their pros and cons, of course, and in numerous situations they can replace one another. However, in the service of targeting audiences comprehensively, marketers likely need a blend of all three channels.