What is the difference between int maxrows=20 and using Integer maxRows=new Integer(20);?

[Sowm Herur]

What is the difference between int maxrows=20 and using Integer maxRows=new Integer(20);?

Can we use int maxrows=20 to store maxrows instead of using Integer maxRows=new Integer(20);?

In what scenarios do we decide on what to use when?

Please Clarify

[Leandro Coutinho]

int x = 10; // x is primitive
Integer y = new Integer(10); // y is a reference to an object

Primitives can't invoke methods of its wrapper classes.
Primitives can't be null, while objects can.

[Campbell Ritchie]

Closing as duplicate.