There's this quote from a book I can't remember;

"A difference that isn't different makes no difference".

That's not the exact quote but it is not without relevance.

The code, in a file of abc, is the text file starting with X: and ending with an empty line.

We then enter this into a converter which displays the notation on a screen and may print it onto paper.

In programs like Sibelius or Musescore, the code of the file, which would be unreadable to us, is immediately entered into an inbuilt converter and displayed, note by note as entered, as musical notation.

EasyABC does the same and I imagine most ABC editors do it too.

When we write a score by hand the code of the file is our knowledge of music and what is written on the paper is the notation.

All three systems have code, converter and display.

I've no doubt that there are advantages and disadvantages in all three methods.

An advantage of abc is the minute size of the files and the wealth of collections of files available on-line.

An advantage of programs like Sibelius and Musescore is their ability to present tablature connected to a score.

An advantage of handwritten notation is that you can write it and read it without any hardware other than pen and paper.

In all three the result is a musical score.

They are only as good as your ability to read them.