Is The island of Cuba is substantially larger than the island of Jamaica?

Yes, Cuba is much bigger than Jamaica. The territory of Cuba is 109,884 square kilometers while the territory of Jamaica is 10,990 square kilometres, which means that Cuba is pretty much 10 times bigger in territory than Jamaica. It might be a bit confusing if you don't know the exact territories because Cuba ranks as the biggest island in the Caribbean and Jamaica ranks as the fourth biggest, so you would assume that their territories are closer in size especially because they are both islands.

Yes. cuba is north of jamaica and it is much bigger in territorial size. Just look for a map both islands are neighboring countries. You will be able to notice the difference in size. Both are beautiful and culturally distinct than the rest of the caribbean in their own right.