Difference between Singleton Class and Static Class

Static Class:

1. You cannot create the instance of static class.
2. Loaded automatically by the .NET Framework common language runtime (CLR) when the program or namespace containing the class is loaded.
3. Static Class cannot have constructor.
4. We cannot pass the static class to method.
5. We cannot inherit Static class to another Static class in C#.

Singleton:

1. You can create one instance of the object and reuse it.
2. Singleton instance is created for the first time when the user requested. 
3. Singleton class can have constructor.
4. You can create the object of singleton class and pass it to method.
5. Singleton class does not say any restriction of Inheritance.
6. We can dispose the objects of a singleton class but not of static class.

OR,

1. A singleton classes allowed to create a only single instance or particular class. That instance can be treated as normal object. You can pass that object to a method as parameter or you can call the class method with that Singleton object. While static class can have only static methods and you can not pass static class as parameter.
2. We can implement the interfaces with the Singleton class while we can not implement the interfaces with static classes.
3. We can clone the object of Singleton classes we can not clone the object of static classes.
4. Singleton objects stored on heap while static class stored in stack.
5. A Singleton class can extend the classes(support inheritance) while static class can not inherit classes.
6. Singleton class can initialize lazy way while static class initialize when it loaded first
7. Static classes are sealed class while Single ton classes are not sealed.