Service is the base class for Android services that can be extended to make any service. A class that quickly extends Service runs on the main thread so it will block the UI (if there is one) and should therefore either be used only for small tasks or should make use of other threads for longer tasks.
IntentService is a subclass of Service that manages asynchronous requests (expressed as “Intents”) on demand. Clients send requests through startService(Intent) calls. The service is started as needed, handles each Intent, in turn, using a worker thread, and stops itself when it runs out of work. Writing an IntentService can be quite easy; just increase the IntentService class and override the onHandleIntent(Intent intent) method where you can manage all incoming requests.
Regards,
Nitesh Bavishiya