Here is a list of what a progressive web application can / should offer:
- Responsive: to fit any form factor
- Connectivity independent: Progressively-enhanced with Service Workers to let them work offline
- App-like-interactions: Adopt a Shell + Content application model to create appy navigations & interactions
- Fresh: Transparently always up-to-date thanks to the Service Worker update process
- Safe: Served via TLS (a Service Worker requirement) to prevent snooping
- Discoverable: Are identifiable as “applications” thanks to W3C Manifests and Service Worker registration scope allowing search engines to find them
- Re-engageable: Can access the re-engagement UIs of the OS; e.g. Push Notifications
- Installable: to the home screen through browser-provided prompts, allowing users to “keep” apps they find most useful without the hassle of an app store
- Linkable: meaning they’re zero-friction, zero-install, and easy to share. The social power of URLs matters.
From these points, linkable was one of the first characteristics imported by native applications from the Open Web in the form of mobile deep linking.
But special mention deserve the combo fresh + installable as it represents one of the main advantages of the Web as a platform over the native alternatives. Here installable means that it appears in your home screen. It does not mean you require to pass downloading and installation stages. You open a URL or discover a service while browsing and it’s done: it appears in your home screen.
Fresh refers to how a regular web works, offering an instant load and seamless updates. You are not asked for installing an update from the web of YouTube, it is deployed and you consumes it the next time you visit it.
I’m not talking about the benefits of the remaining points because you were asking for the differences and, for instance, re-engagement is something native applications already have via push services and notifications and now web applications have caught up.
Other related and key question is about which platform is more suitable for your needs. If you are not accessing special hardware capabilities, the Web should be enough and choosing the web you are free from the marketplaces, proprietary ecosystems and by the way, you can ensure certain grade of ubiquity and interoperability.
As of August 2016, Progressive Web Apps actually offer more hardware access than commonly thought. Here’s a screenshot of whatwebcando.today from my Chrome 52 stable on Android:
Hardware access includes
- geolocation – supported in the vast majority of browsers
- camera and microphone via the getUserMedia/Stream and the upcoming MediaStream Image Capture APIs
- device vibration
- screen orientation and accelerometer access, including compass and gyroscope
- battery status
Upcoming hardware access
These features are being implemented or already work in some browsers:
- Bluetooth via Web Bluetooth API
- ambient light sensor (works in Firefox 48+)
- proximity sensor (works in Firefox 48+)
- accelerometer, magnetometer and gyroscope sensor access
- shape detection API
Another important point to note is that the Origin Trials Framework (implemented in Chrome) enables manufacturers to expose and test hardware (or software) capabilities without having to go through the standardization process. For example, a phone maker could expose an API for reading the values of a pressure sensor, refine it, then submit it for consideration to the W3C.
Besides hardware access, there are also software features traditionally employed by native apps that are now available to web apps.
Traditionally native features that PWAs can also use
- push notifications
- working offline
- adding an icon to the home screen
- appearing in the apps list thanks to WebAPKs – Progressive Web Apps can now be packaged into actual installable Android packages!
- launching in full-screen
- clipboard access
- hardware-accelerated 2D/3D graphics via HTML5 Canvas or WebGL – check some of the HTML5 Canvas demos, WebGL sites or the three.js library. A 2014 benchmark of the Unity cross-platform game engine compared native vs. WebGL rendering performance, and concluded that
“The most important takeaway is, while there are still areas where WebGL is significantly slower than native code, overall you can get expect very decent performance already, and this can only get better in the future.”
- reading user-selected files in any browser
- slick, smooth UIs with 60fps animations
These features cover a lot of use cases, and many popular native apps nowadays could be rewritten as PWAs. Take Slack, for example. Its open source alternative, Rocket.Chat, is building a PWA version. For more PWA demos, see https://pwa.rocks.
Native-like features coming to PWAs
- handling intents — for example, sharing a page to another app, or being the share target, e.g. a PWA chat app that receives an image to set as the user’s avatar
Native Android features that PWAs currently lack
- contacts, calendar and browser bookmarks access (lack of access to these could be viewed as a feature by privacy-conscious users)
- telephony features – intercept SMSes or calls, send SMS/MMS, get the user’s phone number, read voice mail, make phone calls without the Dialer dialog
- low-level access to some hardware features and sensors: flashlight, atmospheric pressure sensor
- system access: task management, modifying system settings, logs
Progressive Web Apps offer features that native apps lack
- discoverability – content in progressive web apps can easily be found by search engines but a content-centric native app like StackOverflow won’t show among app store search results for content that it does offer access to, such as “pwa vs. native”. This is a problem for communities like Reddit, which can’t expose their numerous sub-communities to the app store as individual “apps”.
- linkability – any page/screen can have a direct link, which can be shared easily
- bookmarkability – save that link to access an app’s view directly
- always fresh – no need to go through the app stores to push updates
- universal access – not subject by app stores sometimes arbitrary policies or (unintended) geographic restrictions
- large data savings, extremely important in emerging markets with expensive and/or slow Internet access. For example, e-commerce website Konga cut data usage by 92% for the first load by migrating to a PWA.
- low friction of distribution – if your progressive web app is online, it’s already accessible for Android (and other mobile) users.
- 65.5% of US smartphone users don’t download any new apps each month
- PWAs eliminate the need to go to the app store, search for the app, click Install, wait for the download, then open the app. Each of these steps loses 20% of the potential users.