Greetings Catapult!

Eloah has the right of it here─multiple voidsent can occupy a single hierarchical rung. While lower-level bombs are relegated to the eleventh, higher-level bombs (such as grenades) fall onto the tenth, which also happens to be populated with puddings (funfact: some pudding NMs are found on the ninth).

This hierarchical ranking is a system devised by Eorzean scholars of the void, based solely off their study of the largely unknown realm (much like how demonologists 'rank' demons), and it is safe to say that the voidsent themselves are probably not bound by the definitions that Eorzean mortals have placed upon them to make their understanding of that realm easier.

Hopefully in the future I'll have an opportunity to reveal more of the hierarchy in-game and maybe even sneak in a Lovecraftian quest about a void scholar who is sinks deeper into madness the more he learns of the TRUTH!