All operating systems have their differences when comparing, for instance, a mobile operating system like Android to a computer focused one like Windows. Apple has differences from Windows as well. However, each operating system allows you to do the same or similar things – it may just be a different button to push or icon to click.
Web browsers, applications and file managers will all work in PureOS/Librem in ways that you are used to on other devices. They may look a little different than what you’re used to, but they will get you to the same place.