what is the difference between x86_64 amd64 and 64 bit ? I think its a stupid question but still.

I use a x86_64 bit Ubuntu, but when ever I try to do a live boot of any other 64 bit images like the gnome 3.16 released yesterday it does not work ?

Also some times when I try a virtual machine of a 64bit image it does not work either.

What is the reason for the same ?

My laptop model is an Hp Pavillion dv4 1506tx. The processor is 2.20 GHz Intel Core 2 Duo Processor T6600

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    possible duplicate of My processor is 64-bit - does that mean I need the amd64 image? – muru Mar 26 '15 at 13:29
  • When you try to run a virtual machine, what error message do you see? Your CPU lacks some hardware (VT-x) that most 64-bit CPUs have, so 64-bit VMs may not run or may run only after editing a configuration file. – Mark Plotnick Mar 26 '15 at 17:32
  • First of all i don't have an option in my virtual box to create a 64bit VM. All i have is 32 bits. Even though my Os is 64 bit. And if I try to install it says incorrect Kernel. – jgm Mar 26 '15 at 18:49
  • Also if my processor is 64bit does it still need visualization support to run a 64bit os as virtual machine ? And why does a normal 64 bit doest work in mine even to boot as live? – jgm Mar 26 '15 at 18:54
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    They're all the same , but amd64 is the naming used om Unix/Linux for historical reasons. – Sergiy Kolodyazhnyy Apr 2 '16 at 12:13

This may not solve exact problem, but I'll clarify the difference between x86_64, amd64 and 64-bit.

Every micro-processor implements an instruction set (also called instruction set architecture or ISA in short).

64-bit ISA or 64-bit processor that the length of address bus is 64 bits. Intel/AMD have variable length instructions - they vary from 1byte to 15 bytes. So, instruction length does not determine what type(32/64-bit) processor it is.

x86_64 is name of specific 64-bit ISA. This instruction set was released in 1999 by AMD (Advanced Micro Devices). AMD later rebranded it to amd64.

Other 64-bit ISA different from x86_64 is IA-64 (released by Intel in 1999).

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  • +1 Also CPU's have a Data bus and an Address bus - both are 64 bit in x86_64 (aka amd64). Intel Pentium 32 bit refers to the Address bus hence 4GB physical memory limit but it employed a 64 bit Data bus. – Tino Mclaren Apr 10 '19 at 13:06

Actually... AMD64 is the real 64 bits architecture that AMD created and intel licensed it and uses it even today (just as AMD had the license to use x86 on the 32 bit CPUs). x86_64 far as i know is nothing more than a 32 bit CPU that can address the extra memory that a supposed 64 bit system need (so like a 32 bit system that recognizes and uses more than 4GB of RAM).

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  • How is this different from the existing answer? – Thomas Ward Mar 2 '18 at 14:43
  • No, x86_64 is the real 64bit architecture. You are conflating it with i686 PAE (physical address extension implemented using virtual memory tables of operating system) which extends memory support beyond 32bit memory space (beyond 4GB). – MariusM Mar 11 '19 at 9:55
  • x86 is a family of instruction set architectures, and it has different bits like 16-bit, 32-bit, and 64-bit. So I think you are wrong about 32bit. FMI please check this link – scarface_90 Mar 3 at 11:09

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