Just because it's fast, it doesn't mean it's espresso
Let's get a few things out of the way quickly. Espresso doesn' mean fast or express. It translates to pressed out coffee. Also, and this one may make a few people's eyes twitch; in French culture, it is perfectly acceptable to call it expresso as that is the french translation of espresso.
What is Espresso?
Espresso is created by forcing steam through roasted ground coffee beans. Breaking that down, one could say a Moka Pot makes espresso. Which is hard to argue against as so many people use moka pots at home in Italy and worldwide. Its similar but its not espresso as the pressure in a moka pot isn't anywhere near the 9 BAR of pressure that an espresso machine will use to extract coffee from bean.
Does my Aeropress make Espresso?
I love my Aeropress, but its still not espresso, as it uses hot water (not steam) to make a concentrated coffee. But it does use some pressure to create a lovely cup of coffee.
Is Nespresso Espresso?
Nespresso machines are very interesting as they can blur some lines. They don't use the amount of pressure a conventional espresso machine uses, but they produce something very similar in appearance, volume, and taste to conventional espresso. I really can't fault anyone for having these machines and calling their drink espresso. I'm sure there are plenty of espresso purists that would fight me to the death on this, but at the end of the day, if it looks like a duck, sounds like a duck... well you get the picture. I will aruge this though, you will never get the same quality of espresso drink from a Nespresso, that you would from your local specialty coffee roaster.
At the end of the day, this is all very snooty from an outsider looking in, and even in writing this it feels quite snobby. It is important however to distinguish one from the other. If you went to Starbucks and they made your latte with a moka pot or aeropress, im sure you could taste the difference. It's close, but it's not the same. A Maserati isnt a Ferrari. It's close, it's still a very nice car, but it's not a Ferrari.