Your OS is 64-bit but your browser, Firefox for example, may be 32-bit. When you go to download Java it usually recognises the browser that you are using. The quick way to check whether you are using a 32-bit or 64-bit browser is to...
In 64-bit versions of Windows, you can determine whether you're using a 32 or 64-bit browser in the Task Manager:
Pressing Alt + Ctrl + Delete at the same time. Clicking Task Manager. Click the Processes tab. The number that appears after the process for your browser indicates the version in use.
It is the browser that determines which version to use - Firefox is 32-bit and so I believe is Chrome, except for Linux.