Most of my bells are made of bronze or bell metal. This is an alloy of copper and tin. I asked John Taylor Bell Foundry to define the distinction between bronze and bell metal. This was the reply:
Bell metal is just one of many variants of bronze, we only call it that because we use it!
Handbells have less tin-20% or so and small carillon bells have more, up to 25%.
Hope this helps.
So there you have it!