The word “ seraphim” is again spelled “seraphims,” and “has” is spelled “hath” in the KJV. These are the only differences, other than punctuation, and so only the Book of Mormon text is quoted here.
The live coal laid upon his mouth would be analogous to his being “wrought upon and cleansed by the power of the Holy Ghost” referred to by Moroni in the Book of Mormon (Moroni 6:4, see also 2 Nephi 31:17). Isaiah’s sins were forgiven (v. 7).