key points about difference betweeb interface and abstract class

this is simple question and be asked almost all interviewing,the most importance thing is to mention the key points
1)Interfaces are just signatures and have no implementations (code in method bodies) where as abstract classes can have some implementations.
2)You can extend only one abstract class but you can extend (or implement) multiple interfaces
3)Interfaces define a contract or signature and have no behavior but abstract classes have behavior