Umm, the Windows 7 bootloader is present in Windows 7 and the Windows 8 bootloader is present in Windows 8. So I don't understand your question.
Each version of Windows installs its own bootloader. If you multi-boot different versions of Windows on your machine, it's important to install them from oldest version to newest because newer bootloaders support older OSes but not vice-versa.
Could you make it a little clearer what you want to know?