Yes, they look very similar, but to a computer they're as different as I and l (capital eye, small l) or O and 0 (big letter oh, digit zero).
The Latin letter is "n", yes, and the Greek letter with the same sound is ν (not v). The capital versions look exactly the same (latin N, Greek Ν).
You'll have to switch your keyboard to Greek to type Greek letters -- https://www.duolingo.com/comment/17706271 has some pointers.
By installing a Greek keyboard layout.
That won't change the physical keyboard but it will let you type Greek letters with your existing keyboard once you activate the Greek keyboard layout. Afterwards, you can switch back to your Latin-based keyboard layout.
https://www.duolingo.com/comment/17706271 has some links for adding a Greek keyboard layout.