Real World one entity represents by Java Instance. We can create instance using Class Name. Further instance dependent variable represents by instance variable, class dependent variable represents by static variable and method specific variable represents by local variable. Instance dependent behaviors represents by instance method, class dependent behaviors represents by static methods.
Instance variable , static variable are global variable , because these variable can be access to outsiders. But local variable is valid inside the particular method scope only. Further instance variable , static variable assign default value when it is initialized. But local variable must be initialized.
Instance method, Instance variable can be accessed only particular instance of a class. Static method can be access directly inside the class. If class methods access from outside then use class name for access it.
Try to Understand. Complicated things comment me. I resolve the issues.