Explanation: https://docs.vmware.com/en/VMware-vSphere/8.0/vsphere-lifecycle-manager/GUID-9A20C2DA-F45F-4C9B-9D17-A89BCB62E6EF.html
A vSphere Lifecycle Manager image can consist of the following four elements:
ESXi base image
The base image contains an image of VMware ESXi Server and additional components, such as drivers and adapters that are necessary to boot a server. The base image is the only mandatory element in a vSphere Lifecycle Manager image. All other elements are optional.
Vendor add-on
The vendor add-on is a collection of software components that OEMs create and distribute. The vendor add-on can contain drivers, patches, and solutions.
Firmware and drivers add-on
The firmware and drivers add-on is a special type of vendor add-on designed to assist in the firmware update process. The firmware and drivers add-on contains firmware for a specific server type and corresponding drivers. To add a firmware and drivers add-on to your image, you must install the hardware support manager plug-in provided by the hardware vendor for the hosts in the respective cluster.
Independent components
The component is the smallest discrete unit in an image. The independent components that you add to an image contain third-party software, for example drivers or adapters.
