The distinction between these two is not always clear, but I have found this a useful schema for thinking about system architecture that I’ve also heard discussed in other contexts as well.

Simple here means choosing an architecture that gets from input to desired output in as few steps as possible. Easy here means choosing an architecture that can be built quickly, or is in some way convenient.

Simplicity and easiness are not mutually exclusive, but when they are not perfectly aligned, I believe always pushing for simplicity reduces the burden of maintenance and long-term costs.