The distinction of "button" ears and "rose" ears refers to their position on a dog's head and how the position alters the dog's overall appearance. This distinction has little bearing on a dog's personality, but can make a large difference in appearance.
The fold of button ears should be level with the top of the dog's skull. The fold of rose ears are positioned so that the ears are angled towards the front of the head.
The hard angle and slightly larger size of the button ear lends the pug a larger appearance. Rose ears make the dog's face appear slimmer and smaller for the same reasons.
"Flying button" ears appear as a cross between the two ear variants. They are positioned closer to the top of the head. Ears can be positioned further apart or closer together than the standard. Some pugs may have one button ear and one rose ear.
Knowing whether your pug's ears are button style or rose style is of little importance unless you are entering him in a dog show. Button ears are preferred at American Kennel Club events.
It is rumoured that Napoleaon Bonaparte refused to allow his wife's pug to sleep in their bed at night. His wife stated that if the pug wasn't allowed to sleep in the bed, she would not sleep there either. The dog was then allowed to rest with them.