Minecraft wiki entry for Structure_Block, associated text: Block Appearance Notes
Air
minecraft:air Not distinguished from other air types, which is not a bug[1]
Cave Air
minecraft:cave_air Not distinguished from other air types, which is not a bug[1]
Void Air
minecraft:void_air Not distinguished from other air types, which is not a bug[1]
Structure Void
minecraft:structure_void
Barrier
minecraft:barrier
Light Block
minecraft:light