It's of course a similar game but they're so different.

Angband is one of those games that are about endless grind, trying to get those rare item drops that allow you to descend a bit further by offering some form of elemental resistance you lacked. And then you can continue grinding. Also, later on, many fights with unique monsters with extremely powerful attacks.

Nethack is much more about getting a collection of items and then trying to figure out how to identify them until you have enough of the important ones,and not running into random deaths. And a lot of fun because all the obscure interactions that can happen.