Clawhammer said:
cast = poured (look a little rougher, carry virtually no premium)
minted = stamped (or sometimes milled, better looking, carry a higher premium)
The two terms were more commonly applied to coins in the old days. Genuine coins were made in a big stamping press to achieve a high detailed design. This technology was so expensive only the government/king could afford it. Counterfeiter's would copy the coin, but could only cast the coin in molten metal from a forge... hence the term 'forgery' !
If you're purely an investor, go for the big bulk cast bars.
If you're speculating (i.e. on the popularity of 1 brand of bar over another) then go for minted bars and coins. There's the potential of more reward, but there's a risk the bars you buy may become unpopular, and you won't make good on the premium you paid for your exotic bars.
Perth Mint = Cast, Australia produced
NTR Metals = Minted, United States produced
But why NTR Metals is cheaper than Perth Mint?
See Bullion Bourse, Bullion Money and KJC. They sell NTR Metals is cheaper than Perth Mint.
Why?