How are international phones different then phones in the U.S.?

[crammpa]

Why is a Samsung Galaxy Alpha (sm G850A) from California or Florida different then a Samsung Galaxy Alpha (sm g850FQ, F, M, K, L, S) from Germany or Australia? I understand that the laws and cultures are different. Is it a CDMA/GSM difference? Most of North America is CDMA but some carriers in the U.S.A. are GSM. My Samsung Galaxy Alpha is GSM from California but is completely different then a Samsung Galaxy Alpha GSM from Canada.