I have read all the reply's, but for me this is the explanation:
The basic difference is that an interface is like a 100% abstract class, that means ALL of his methods are abstract, ALL. But an Abstract class can have, non Abstract methods too, so you have an specific behaviour, this is one's of the differences, think about it, you are getting a more specific behaviour with an abstract class.
The other difference is that in
JAVA you can not extend more than one class, if you make an abstract class, you have to extend it, and you can not extend any other class, you loose that posibility. But is different with an interface, you can implement one or more interfaces, and have the posibility to extend any other class, so is more flexible, depends on what you need.
I hope this could help you, Bye.
Christian Polychroniadis soon SJCP...