what is difference between static methods and non static methods in Salesforce?

hello Uday

****Static Method****

Static methods can be used without instantiating a new instance of the class.

public class Utils {
public static String getHelloWorld() {
return 'Hello World';
}
}

These methods can be called directly

String salutation = Utils.getHelloWorld();

****Non-Static Method****
Non-static method  must have a new instance of the class instantiated in order to be used. Typically these rely on data inside the class that then is referred to inside the class

public class Utils {

public String getHelloWorld() {
return 'Hola Mundo';
}

This version of the method requires us to create a new instance

Utils a = new Utils();

String require =a.getHelloWorld();