Parallels, as you know, allows you to run Windows on a MacBook Pro that is booted normally in to MacOs. The parallels Windows environment is distinct and separate from MacOs, but you can share files between them, and usually you can share printers.
Boot Camp, on the other hand, allows you to boot your computer in to Windows as if it were a windows PC. the MacOS is not running at all. You will have no access to your Mac applications while in Windows Boot Camp. You will only have read-access to files stored on your Mac Disk drive; the windows files will be entirely separate. Parallels works pretty well running Windows as a VM, but occasionally there are glitches or incompatibilities. There would be fewer or more likely no such incompatibilities when you boot in to Boot Camp Windows.
You can also run the version of windows you install in Boot Camp as a virtual parallels machine on computers with single internal drives such as the MacBook Pro. this gives you almost the best of both worlds - you can boot in to Boot Camp when you need to, or you can run windows under the Mac OS. If you install an application in Boot Camp, it will also be available in parallels, since they are "the same". There are a few limitations, though. YOu will not be able to make snapshots (backups) of the Boot Camp environment in Parallels, the way you can with a normal parallels VM.