Hi,

Your code/image is not visible in your questions.

when we check regarding the difference between xpath and field.

We can use both. 

Xpath gives you the option to add below details to an already existing view.
new pages, 
groups, 
fields and more
When you inherit an existing view in a module and required to extend it, you will need XPath expressions.
In complicated situations, you can use Xpath or otherwise the one that you mentioned in the blog.

Regards