Ambiguity around interpretations of a few words:
"1,000,000,000 (one billion, short scale; one thousand million or milliard, yard, long scale) is the natural number following 999,999,999 and preceding 1,000,000,001. ... Previously in British English (but not in American English), the word "billion" referred exclusively to a million millions (1,000,000,000,000)." (google whats a billion)