Nephi – ISIS What is the difference?

Seems to me the only difference between ISIS and Nephi is whether or not you actually believe God is (or was) talking to these individuals. 4:12 And it came to pass that the Spirit said unto me again: Slay him, for the Lord hath delivered him into thy hands;
4:13 Behold the Lord slayeth the wicked to bring forth his righteous purposes. It is better that one man should perish than that a nation should dwindle and perish in unbelief.
4:14 And now, when I, Nephi, had heard these words, I remembered the words of the Lord which he spake unto me in the wilderness, saying that: Inasmuch as thy seed shall keep my commandments, they shall prosper in the land of promise.
4:15 Yea, and I also thought that they could not keep the commandments of the Lord according to the law of Moses, save they should have the law.
4:16 And I also knew that the law was engraven upon the plates of brass.
4:17 And again, I knew that the Lord had delivered Laban into my hands for this cause — that I might obtain the records according to his commandments.
4:18 Therefore I did obey the voice of the Spirit, and took Laban by the hair of the head, and I smote off his head with his own sword.