Queen vs Matriarch

I’ve been playing this game for a while, and I am absolutely loving the boss fight events in this game. Both the Matriarch and Harvester events are cinematic, intense, and give some really good goop.

But it dosent make sense to me why the Queen and Matriarch both exist. Despite their obvious physical similarities, why wouldn’t arc just use the matriarch to defend the harvester or vice versa. it doesn’t make sense that they would allocate the resources to make two separate machines, when just one could easily do the others job.

The same goes for embark, why create to separate enemy’s when just one could easily do both roles. I’m just a little confused by this and hoping you guys might have an answer.