It's important to remember that down is very soft. No matter how much down we use to make a pillow it will still be soft but it will be thicker. Thicker pillows feel firmer. So a firm pillow may have more down inside than a medium down pillow pillow but it will still be soft.
It's almost easier to think of a firm pillow being thicker than a medium pillow. The more down we put into the pillow the thicker it gets, the more expensive it gets and the firmer it gets. Firm pillows are thick and ideal for side sleepers with a larger 'Comfort Gap'. Your 'Comfort Gap' is that area between the crown of your shoulder and the side of your head.
Firm down pillows are definitely thick but they are still soft because they are made of down. But that's not the whole story. We also removed all the feathers that might poke you so all that remains is our legendary Hungarian white goose down so they are soft and luxurious.