There is no difference, from:
http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
It's not always necessary to assign a value when a field is declared.
Fields that are declared but not initialized will be set to a
reasonable default by the compiler. Generally speaking, this default
will be zero or null, depending on the data type. Relying on such
default values, however, is generally considered bad programming
style.