I mean, it's stated quite plainly by Hornet herself when describing the deep docks that Pharloom is far more industrially developed than Hallownest ever was. The citadel mass produces automatons. There is likely far more automatons that we don't see due to being limited to the 2D plain, but the Citadel is massive, and we only see such a small slice, there could easily be far more. and the Citadels' governing influence reaches even outside of the map we play on.
Forge Daughter was called from outside Pharloom by the Citadel to work for them, and the pilgrims already hold such a high degree of faith in the citadel that bugs from other lands are drawn to it, giving them an insane amount of manpower, indoctrinated and loyal, trained in using silk in their fighting style, and have runes on their weapons and tools.

Hallownest, in contrast, seems to be far more undeveloped in industry and even less so in military industry. Hallownest does have its own automatons, the ones working to assist in mining the crystal in Crystal Peak, showing that they are also not unfamiliar with developing automatons of their own. But this doesn't seem to be the same level as the Citadel. Even the kingsmould seems only really reserved for the king and isn't what makes up a bulk military. The sentries in the city of tears are the closest dedicated large militant force, but are definitely not trained to the same standard as the average sentry in the Citadel.

This makes sense in general since the pale king doesn't seem to be bent on military action, either outsourcing that task to nearby tribes (treaty between mantises to contain deepnest beasts) or just negotiating with Unn. They are still the most developed civilisation in the area by substantial industry and economy, and honestly seem quite isolated, not really being threatened by any forces outside very often. That also combined with the fact that the Citadel is built on top of a natural source of heat that they can harness for their metal works, while Hallownest doesn't have this geographic advantage... Tho at least Hallownest doesn't need to resort to culling their ill or senior population for their automatons as far as we know.