BOOTMGR
Windows Boot Manager bootstraps the system (starts the loading of an OS on the computer)
BCD
Boot Configuration Data holds information about OSs installed (such as location of the OS files)
Winload.exe
Loads operating system kernel (NTOSKRNL.exe)
Winresume.exe
If system is not starting fresh/resuming previous system this is called by BOOTMGR
NTOSKRNL.exe
Windows OS Kernel
System files
Windows needs a number of files from system directory
Hardware abstraction layer (HAL.dll)
Session Manager (SMSS.exe)
User session (winlogon.exe)
Security subsystem (LSASS.exe)