Angular comes with different types of services. Each one with its own use cases.

All of these services are singletons. You probably want to use Factory all the time.

Provider

• is the parent of all other services (except constant)
• can be configured using `app.config(function(Provider) { ...})
• a little complex

Factory

• simpler than Provider, but without configuration
• definition: `app.factory('name', someFunction)
• someFunction is called when the name service is instantiated and should return an object

Service

• just like Factory, but:
• instead of a funciton, it receives a Javascript class / a constructor function as argument
• simplest service type, but also least flexible

Value

• just stores a single value
• use it like `app.value('name', 'value')

Constant

• just like value, but:
• can be injected everywhere
• is not constant Oo, but may be changed

Decorating services

• useful for extending 3rd-party services
• $delegate is the service instance
  ^

app.config(function($provide) {
  $provide.decorator('serviceToBeDecorated', function($delegate) {
    // modify $delegate by adding functions etc.
    return $delegate;
  });
});

More differences

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

• Prevents you from data breaches and liability risks
• Upgrade at your own pace
• Works with modern Rubies

Read more Show archive.org snapshot

| | Factory | Service | Value | Constant | Provider |
| can have dependencies | yes | yes | no | no | yes |
| uses type friendly injection | no | yes | yes* | yes* | no |
| object available in config phase | no | no | no | yes | yes** |
| can create functions | yes | yes | yes | yes | yes |
| can create primitives | yes | no | yes | yes | yes |

(taken from Angular Guide Show archive.org snapshot . Go there for further explanation.)