Counting newlines in a file
The two versions execute exactly the same steps,
the only difference is the number of intermediary local variables.

Which version is more clear can be a matter of opinion.
Beginners may find your verbose version more clear,
more experienced programmers may find it tedious.

The good thing about the second version is that the local variables mark bigger logical steps that are quite intuitive. With one weakness, the meaning of the lines variable is not immediately clear. If you say "lines", it might mean a collection, or the count of lines.
But actually it's neither, it's the number of newline characters.

By contrast, your version marks the steps in too much detail,
for example it's not particularly interesting that readFileSync(file) doesn't return a String and it needs to be converted.
That step could be collapsed, as it is a too specific implementation detail,
not something "logical".

I think the best of both worlds would be more like this:

var fs = require('fs');

var path = process.argv[2];    
var text = fs.readFileSync(path).toString();
var lines = text.split('\n');
var newlines_count = lines.length - 1;
console.log(newlines_count);


Each step marks a bigger logical step, with slightly more natural variable names.