Answer 1

public method or variable is visible outside class. you can init it directly. for instance: classname.VARNAME = VALUE. main is a point where program begin executing. static means that method is accessible without creating an instance. without it you need first create an instance of a class. and void means that function or method don't return any value, after executing, it returns nothing.

Answer 2

1. public is a key word normally written before a method, it means that this method can be accessed from out side of the class.
2. static is also key word
3. void is the return type of a function, when a function or method has void return type it means this function will return nothing.
4. main is the name of the function from where the program start to execute.

Answer 3

public- method is visible to all
void-method do not have to return a value.
static- means do not need create an instance of class
main-it is a name of method which is call at the beginning
i.e entry point in any program.

Answer 4

They are not related concepts, so it's hard to tell a difference...
Public: access modifier, accesible by any class
Static: no need to instantiate it
Void: returns nothing
Main: starting point of an application