Why does my 2013 Hyundai Equus 5.0 have two different size air filters under the hood?

Two separate size filters under the hood? Or are you comparing an engine air filter to a cabin air filter?

No it's not the cabin filter (behind the glove box). I have a "main" air filter and there is a small air filter called a chamber filter under the hood near the front. The filter is about 4 inch's tall and 8 inch's wide.