In drop reports, red ship names indicate notable drops. Some of the ships would be listed as "Shipname (Difficulty +)." For instance, if it reads Isokaze (Medium +), that means that, so far, reports say Isokaze mostly drops for Medium or above, that does not mean Isokaze does not drop in Easy, just that there haven't been sufficient reports to show Isokaze also drops in easy difficulty. And also, just because drop reports exist does not mean the drop rate would be equal across different difficulties, and the accuracy of those reports is not 100% guaranteed.