It depends on what you have selected as boot device in your BIOS. Windows doesnt need an EFI partition on your Disk if it find an alternate device if im correct
The EFI System Partition has .efi files. But also does C:\Windows\Boot\ Which EFI files do you think it's booting from? From the EFI System Parition or in C:\Windows\Boot\ ?
This "Boot" tag just indicate that it's the current OS partition, it doesn't mean it has the booting files or Windows Boot Manager the partition with "System" tag contain them
The UEFI BIOS will scan all hard drives, USB drives and CDROM drives in the order specified in its setup. On each hard drive, it will check if it is a GPT formatted drive. If it is not, and legacy mode is disabled, it will move to the next drive. If it is GPT, it will then search for an ESP (EFI System Partition). If none is found, it will again move to the next drive in the list. If an ESP is found (it need not be the first partition on the disk), it will search for a file called BOOTX64.EFI (or BOOTIA32.EFI) in \EFI\BOOT. If this file is not found, again the disk will be considered non-bootable. If found, this file will be loaded in memory and executed, taking over booting process. USB drives can be either MBR, GPT or "superfloppy" and still be considered bootable, as long as they are formatted with the FAT file system (FAT12, FAT16 or FAT32) and have a file called BOOTX64.EFI (or BOOTIA32.EFI) in \EFI\BOOT. CDROMS need to be created with a special hidden "partition", but this partition must also contain a valid BOOTXXX.EFI file in \EFI\BOOT. Il all available drives are scanned in order, and none has a valid boot structure as described above, then UEFI boot fails and the BIOS enters console mode. So in response to the OP: In the situation you describe, yes, the UEFI BIOS first boots to your HDD that is GPT formatted and has an ESP in which it find a valid \EFI\BOOT\BOOTX64.EFI. This files then directs the system to \EFI\Microsoft\Bootmgr, which loads the BSD and continues the booting process. In your case, the BSD instructs Bootmgr that the Windows System partition in on your SSD (as can be shown by the command BCDEDIT), and system initialization continues from there.