To be clear there are currently two distinct applications and they function differently.
1. Lightroom Classic latest version 10.3 you can refer to this application as LrC. This application is the newest evolution of the original Lightroom which began in Feb 2007. Original files are on storage in your computer system as is the Catalog functions.
2. Lightroom is a new application latest version is 4.3 you can refer to this application as Lr. This application was released around 2016. It is the Cloud - Based application original files are stored in the Adobe Creative Cloud. The “catalog” function is also carried out in the Adobe Creative Cloud.