Windows fill in catalog
Update for Windows 7 could refer to systems running Windows 7 32 bit or both 32 and 64 bit Windows 7 in general.
update for Windows 7 for x64-based systems means the bring up to date only applies to systems running Windows 7 64 bit.
32 and 64 bit or x86 and x64 refer to the computers processor architecture.
A computer with a 32 bit processor and use up to 4 GBs of RAM while a computer with a 64 bit processor can address up to 192 GBs of RAM.