java sdk x86 and java sdk x64 what is the difference

java sdk x86 and java sdk x64 what is the difference ? Machine is 64-bit cpu arguably the selection x64, but I still have this question , x64 and x86 of java sdk java sdk in the end what is the difference ? Development differ ? ?
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no difference for us to develop , but their implementation is based on a different operating system instruction set and architecture.
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theoretically need to use the 64-bit x64-
But the difference is very small, running on x86 64-bit is no problem .
personal feeling is that if there are several differences should be about the underlying memory read or access it.
not too much.