They are often mistakenly used in the same way, but they aren't quite the same.
The default constructor is the constructor that is inserted by the compiler automatically if no other constructor is provided. This is always a no-argument constructor. But if you provide your own no-argument constructor then that isn't a default constructor.
If you look at the meaning of "Default" closely.. you can understand why ?
This is definition for the default in oxford dictionary : - "( computing ) what happens or appears if you do not make any other choice or change "
I think , You have already found the answer yourself, if you have really studied the
Default Constructor
If a class contains no constructor declarations, then a default constructor with no formal parameters and no throws clause is implicitly declared.