Bootcamp User Interface
Bootcamp Assistant UI can be confusing and may not show options as you expect them.
The main screen has three different variants.
On 2011 and older Macs, with built-in Optical drives, the screen will show two options. These Macs require a physical DVD to enable the last option - Install . It will change to Remove, if Windows is already installed via Bootcamp. These models look for a Hybrid MBR to decide if Windows is installed or not.
The Download option requires a USB Flash drive which will be erased and formatted as a MBR disk using FAT32 file system. (Update: Use exFAT instead of FAT32 for W10 2018 and later ISO images).
On 2012-2014 Macs which do not have built-in Optical drives, you can use a Windows ISO from Microsoft using Microsoft.com Software Downloads .
On 2012 models with built-in Optical drive, a USB Windows Installer and the built-in Optical drive, both are supported. Macbook Air models can use an external Superdrive or create a USB Installer using an ISO file.
The last option changes from Install to Remove, if Windows is detected.
2012 and older Mac models only support legacy BIOS/MBR installations and restrict partitioning to four (4) partitions - EFI, OSX, Recovery HD and Windows. Creating additional partitions can cause Windows to be corrupted or stop booting.
macOS High Sierra and later use APFS as the default file Container and file system scheme. macOS Big Sur adds OS snapshots. For APFS-based systems, the disk partitions are EFI and a APFS Container for all necessary volumes. Recovery HD is no longer used. There is a separate Recovery volume within the APFS Container. As of this writing macOS Big Sur EFI is problematic.
Using GPT Fdisk to manipulate the MBR is an option, but it creates complications, when you choose to upgrade OSX versions as the custom layout may not be recognized by all versions of OSX.
Early 2015 models can behave similarly under Yosemite or older versions of OSX.
Late 2013 and 2014 models support EFI/GPT and BIOS/MBR installations.
2015 and later models only support Windows 8.1 or higher using EFI/GPT. Windows 7 is no longer supported on these models. These models do not have a task list on the UI. They need an ISO file and need partitioning to start the installation.
MacOS Mojave and later do not support W8.1. You must use W10 ISOs.
References
- Boot Camp for Mac: Boot Camp Assistant overview / Get started with Boot Camp on Mac - Apple Support
- Boot Camp Assistant User Guide for Mac - Apple Support
- Boot Camp Control Panel User Guide for Mac - Apple Support
- How to install Windows using Boot Camp - Apple Support
- Boot Camp for Mac: Remove Windows from your Mac
- https://help.apple.com/bootcamp/mac/5.0/help/ (Legacy)