The simplest way to separate them is by looking at the positions of the male and female flowers. In Typha latifolia the male flowers sit directly above the female flowers while in the hybrid there's about a one inch gap between them. Obviously, we are looking at last year's flower heads which makes things harder to discern, but I'm fairly certain I can see where the male flowers were and the gap that separated them from the female flowers.
Typha latifolia has "thicker" heads than the hybrid. I tell people 'If the head is shaped like a corn dog, it's probably common cattail. If it's shaped like a hot dog, it's more likely the hybrid. Lastly, the hybrid is much more aggressive than our original cattails and forms dense, nearly mono-cultural stands wherever it finds favorable conditions. Your first picture just has the "look" of a stand of hybrid cattail.
