Cloud based software solutions have full functionality for document editing and most of the functionalities you can use free of charge.
Online presentation apps give you an opportunity to present and edit a slideshow wherever you like, because it’s working over the Internet.
You can have your presentation online and use it as a backup and if something accidentally goes wrong with USB stick where the presentation is stored, you still have an online copy from it.
Saving from one format to another can cause a total loss in the presentation design. It can happen when you are editing and presenting with different software or even between the same presentation software witch has different version.
Online presentation has the same look everywhere you present it, because it is working in the browser.