Singleton is use same object for all the request form the client side, means if first request comes to server it's generate the object and all are request will share same reference like score or stock sharing and if the Server will not get any request withing 5 minutes then it will destroy the object and again will create and repeat the same processSingle call: Each and every request will served one object at once. ATM machine has been designed on Single Call mechanism so that after one transaction will ask your card swipe again and do the same procedure for transaction.

Singleton: A single object instance services all client requests. Singletons guarantee that only one object instance is in memory at any time per application domain.this single object will be created when first request come for that object

Single call. Each client call is serviced by a new object instance. No state management is provided by this model. This model is well suited for load balancing and increased scalability