It's mostly regional variation rather than brand names. American English almost always uses "cotton swab" as the generic term while British English today uses "

It's mostly regional variation rather than brand names. American English almost always uses "cotton swab" as the generic term while British English today uses "cotton bud" more often. Overall "cotton swab" appears to be the most common English term. Given that "cotton bud" appears to be a relatively recent British quirk (gaining popularity in the last couple decades), I would submit that "cotton swab" is the original and proper generic term. British English: https://books.google.com/ngrams/graph?content=cotton+swab%2Ccotton+bud&year_start=1800&corpus=18 https://books.google.com/ngrams/graph?content=cotton+swab%2C... American English: https://books.google.com/ngrams/graph?content=cotton+swab%2Ccotton+bud&year_start=1800&corpus=17 https://books.google.com/ngrams/graph?content=cotton+swab%2C... English overall: https://books.google.com/ngrams/graph?content=cotton+swab%2Ccotton+bud&year_start=1800&corpus=15 https://books.google.com/ngrams/graph?content=cotton+swab%2C... (Refresh the page if the graph doesn't load at first.)