Whats the difference between AMD64 and EM64T?
Both refer to 64-bit processors from AMD (AMD64) and Intel (EM64T). AMD’s 64-bit processors include the Athlon 64, Turion, Neo, Phenom, and Opteron families. Intel’s 64-bit processors include the Core2, Core iX, Celeron, Xeon, and Pentium (all based on the Core2 architecture). The last few versions of the old Pentium 4 and Xeon chips also support EM64T. The AMD line of 64-bit processors were released well ahead of Intel’s offering. Therefore, for historical reasons the arch keyword for all x86-64 compatible architectures is amd64. As such, AMD64 is a generic reference to 64-bit chips, whether AMD or Intel.
