[defconw]

One is cloistered and the other isn't. We have brothers and priests and they have differences as well.

I will say that Sisters who are referred to as Nuns generally don't correct anyone on it.

[Tax-chick]

We have brothers and priests and they have differences as well.

True, but that's not the same. Priests are ordained and Brothers are not, even in the same religious order.

I think the technical distinction between "sisters" and "nuns" is their vows: "nuns" of various orders take permanent vows, while "sisters" take temporary vows (one year, three years, five years).

Thus, you can have "sisters" and "nuns" in the same order, and you can have "sisters" who are enclosed ("cloistered") and nuns who are not.