The short version of the answer is that Lisp is not merely a different notation, it’s a fundamentally different way of thinking about what programming is. The mainstream model is that programming consists of producing standalone artifacts called programs which operate on other artifacts called data. Of course, everyone knows that programs are data, but the mainstream model revolves around maintaining an artificial distinction between the two concepts. Yes, programs are data, but they are data only for a special kind of program called a compiler. — Why Lisp