There are different possibilities that explain why Joseph Smith’s translation of the Book of Abraham does not match up with the translation of the Joseph Smith Papyri. For example, John Gee has concluded from eyewitness descriptions of the artifacts in Joseph Smith’s possession that the Joseph Smith Papyri is not the source of the Book of Abraham. There are a lot of scholastic studies arguing both sides of the issue. It is difficult, if not impossible, to discover exactly what Joseph Smith had in his possession, how he came to have them, how he translated them, and what has since happened to all of these artifacts through a study of history. However, I believe in a God who hears and answers prayers. If we have a sincere desire to know if the Book of Abraham, or the Book of Mormon, is an inspired book, we can study it and ask God if it is of Him. He will let us know.
“And by the power of the Holy Ghost ye may know the truth of all things.” (Moroni 10:5)