The Book of the Dead is a somewhat standardized corpus of Middle Egyptian texts used over a long period of time, including the time when later phases of the Egy

The Book of the Dead is a somewhat standardized corpus of Middle Egyptian texts used over a long period of time, including the time when later phases of the Egyptian language were spoken instead of Middle Egyptian. You're seeing two different scripts, Hieratic (cursive) vs. hieroglyphs rather than two different languages. Both scripts are equally old. (There are other, later funerary texts written in later phases of the Egyptian language that can be said to descend from the Book of the Dead, but the papyri in question are Book of the Dead texts.) If you're interested in reading these texts in translation, Falkner's translation is available in many different editions and would be a good place to start. Just as a warning, these texts require a lot of context to make much sense. There's also a lot of wild, uninformed interpretations out there.