What is the difference between opera and musical theatre?

I’m no expert or even aficionado of either genre.

But I’ve always thought Mozart, Rossini and Verdi would be perfectly happy on Broadway.

Today I read this NY Times piece that make the claim:

“in opera, music is the driving force; in musical theater, words come first. This explains why for centuries opera-goers have revered works written in languages they do not speak.”

I’m not buying it. I bet audiences in China and France would love West Side Story with subtitles or a detailed printed program.

What do you think?