IUPAC DOUBT

what is diff bw geminal and alkylidene ? https://preview.redd.it/74i4gpozedae1.png?width=1920&format=png&auto=webp&s=570efd20d7a9988cba1a6d6be1f7c5c5797fdc47 yha p sir n geminal aur alkylidene dono k hi structure same bnaya h