Could you please explain if there is any difference between 'a blunder' and 'a mess-up' in the following examples:
McDonald's made a classic sales promotion blunder with its heavily advertised 25th anniversary offer.
A mess-up in production meant there were 800,000 bottle tops which had the winning number and Pepsi paid out more than five times its budget before it stopped paying out prize money.
Are these words just synonyms and their usage makes the text more interesting to read?
Thank you in advance.
They mean very similar things. I would say that blunders are always foolish and embarrassing, but they may not be serious (although they usually are). Mess-ups are serious botches that could perhaps not be embarrassing. They usually are of course, but I think it's not included in the word's meaning.
"Mess-up" is a colloquial word and "blunder" isn't.
Please note that most of what I have written is speculative. I'm not sure about it.