The other two have lots of fancy things done to the mRNA itself, including pseudouridine substitutions, 3 and 5 prime untranslated regions, and a poly-a tail. The payload comes from the NIH, and is modified by them as well with proline insertions to stabilize the spike in the prefusion form. All current EUA vaccines in the US (BioNTech, Moderna, Jansen), plus NovaVax (code not delivered to the user in that case) use some form of the NIH payload, as far as I can tell.

Edit: I forgot about the proprietary mRNA delivery systems as well, I don't really know much about those.