How many ways to update ESX/ESXi host

To my understand there are 3 ways to update ESX/ESXi host.

• VMware Update Manager
• VMware Host update Utility
• vihostupdate

VUM - update host, vm, vApps and templates (this one I am sure)

VMware host update utility - only update the host?

vihostupdate - can do the same as VUM and the only difference is that it is a command line interface?

Is there a VMware document that I can read up on this.  I am asking this because I am preparing for VCP 4 exam.  In the place I work, we are using vSphere 5 and we never have to upgrade from 3.x to vSphere 4.

Thanks for the pointers and have a nice day,

anthony.