On the web a subset of web sites are web apps. These are web sites that have app like behavior - that is a user might call it an app like Outlook, Maps or Gmail. And they may also have a W3C app manifest.
A subset of web apps are progressive web apps. Progressive web apps are web apps that have a W3C app manifest and a service worker. Various OSes are beginning to support PWAs as first class apps on their platform. This is true for Win10 as well in which PWAs are run as a WWA.
Within that we have a notion of a packaged web app and an HWA (hosted web app). There's no real technical distinction for the end developer between these two. The only real difference is whether the StartPage identifies remote HTML content on the web (HWA), or packaged HTML content from the app's appx package (packaged web app). An end developer may create an app that is a mix of these as well, with HTML content in the package and HTML content from the web. These terms are more like ends on a continuum and identifying two different developer scenarios since the underlying technical aspect is pretty much identical.