What's the difference between a Multiple pages PWA with a SPA pwa?

recently I created a SPA with angular and I config it to be PWA ( a Single page Application that is PWA) and recently I found that we can also change a regular web page (MPA) to PWA as well

So my question is

what's the difference between a Multi pages web (config to be a pwa) with SPA (config to be a PWA)?

all of us know that most important benefit of SPA is a without refresh webpage so when I create a regular web app and config or convert it to a PWA and when it save on Mobile or local storage then the End user can't see or fill the refresh on the Page because its fast load so

why we have spend more time to develop a SPA and change it to PWA when we can easily create a regular webpage and change it PWA? thanks in advance