Uranium Bombs
The first test at Alamogordo was to test the more economical and complex plutonium device. The first bomb at Hiroshima was the crude and expensive uranium device and the one at Nagasaki was plutonium.
I think it may be possible that if you look at their shape all the subsequent aircraft A-bombs were plutonium devices. I would be happy to be corrected on this. in a rational way.
The device we first tested at Monte Bello had plutonium from the Canadian reactors in it.