What is the difference between a biomass pyramid and a pyramid of numbers

A biomass pyramid shows the mass that each trophic level are producing overall. e.g., 10 000 kilograms of grass - 1000 cows - 100 kilograms of meat.
A pyramid of numbers shows how many animals in numbers are on each trophic level. E.g., 100 kookaburras - 20 snakes - 100 insects. A pyramid of numbers is not necessarily triangular in shape all the time.