Inaccurate word counts

[Woody44]

I just entered a writing competition for short stories, with a strict limit of 650 words per entry. The site provides a link to a web site that they use as the official word counter for their competitions.

I wrote a short story that was initially over 750 words according to TextMaker. However, according to the official word count web site I was under 700 words -- still too long, but not by as much as I had feared. I made a few deletions and rechecked it. The official word count was now 646 words. I submitted it.

BUT ... TextMaker reports the word count as 677 words, a discrepancy of 31 words. Out of curiosity, I entered the exact same text into LibreOffice Writer, and Microsoft Word. Both reported the word count as 648 words.

Why is the word counter in TextMaker so different from everywhere else?