Difference between abstract class with all method abstract and interface?

Question

I had an interview where interviewer asked me first what is the difference between abstract class with all the methods abstract and an interface.

I replied that if

Answer 1

For the first situation i'd chose interface over abstract class with all methods abstract as having interface leaves me with option in future for my implementing class to extend some other (abstract) class.

For second scenario, if you really don't want your concrete class to extend any other class and also want to "implement" contract, you can have abstract class with all methods abstract.