Looking at a backlit screen is like looking into a light bulb. A backlit screen is bright, even in a dark room. Your computer screen is a backlit screen.
An e-ink screen is not lit. Just like a piece of paper, the only way YOU can see it is if you shine light ON it. You can read an e-ink screen in a well lit room, but if you were sitting in the dark you would not be able to see it without some other light source. .
That’s it. It’s that simple.
Backlit = bright. E-ink = not bright.
Now for a few other points about each:
Backlit screens are found on desktop computers, laptops and tablets (like the iPad and the Kindle Fire).
Backlit screens wash out in bright sunlight.
The use of backlit screens before bed (like with a tablet) makes sleep difficult for many people.
Some people complain of eye strain with extended use of backlit screens.
E-ink screens are clear and sharp in bright sunlight, making them the #1 choice for outdoor (beach) reading.
To read in a dark room, (bedtime reading), you need a light. A clip on book light works great for most e-readers.
The Paperwhite Kindle has an e-ink screen. It is unique in that it has a built in light that covers the whole screen. The light reflects, it does NOT come from within. If you turn the light up, the screen looks bright, but that is light that is layered on TOP of the e-ink. If you turn the light down, you will see the standard plain old e-ink screen. So the Paperwhite is just an e-ink device with a fancy light.
One more piece of confusion to clear up: Kindles come in both backlit AND e-ink screens. Kindle Fire Tablets have backlit screens. Kindle e-readers have e-ink screens.