iPhone XS Vs iPhone XS Max: What's The Difference?

Apple's new iPhone XS and iPhone XS Max are the biggest, most expensive iPhones ever made but what are their differences and should you upgrade, or not?
ref:https://www.forbes.com/sites/gordonkelly/2018/09/13/apple-iphone-xs-vs-iphone-xs-max-whats-the-difference/