When is your bronze birthday?
There really is no bronze birthday year but there is a golden birthday, which is the year when you turn the age your birthday falls on. If your birthday is the 15th, then your golden birthday is the year you turn 15.
Yes, there is a difference, but is less important than the difference between solid (sheet) bronze and cast bronze caskets. Solid bronze caskets are welded from sheets of wrought bronze. Bronze deposit caskets too, but they have an additional coat of bronze which is applied by an electrolytic (or similar) process to a base made of sheet bronze. This increases the thickness of the bronze walls and guarantees a smooth surface.