There are various ways to install Ubuntu Linux, namely single boot installation, dual boot installation, installation with virtual box, or installation on Windows Linux sub system.

Then what makes installation process different?
Definition of Terms in Operating System Installation
- Single Boot Installation
Single boot installation is installation of one operating system in one device (hardware).
For example reinstalling Windows, reinstalling Linux Ubuntu with a flash drive and so on.
- Dual Boot Installation
Dual boot installation is the installation of two operating systems in one device (hardware).