To me the biggest difference is the three theoretical papers, including from very reputable sources, all showing that a) there is indeed something weird going o

To me the biggest difference is the three theoretical papers, including from very reputable sources, all showing that a) there is indeed something weird going on with this material and b) due to the unusual configuration it is going to be tricky to manufacture. Fleischmann & Pons was never supported by theory and was essentially a "we measured something and have no idea what is going on". LK-99 is more of a "the theory says something interesting will probably happen, and we believe we measured it in some samples but can't reliably reproduce it".