I've been buying my shoes and boots mainly from Ebay, and occasionally from local stores. I've been looking for boots on Amazon in order to grab a bargain because time is getting hot on the northern hemisphere

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I'm used to European sizes, and I know I should look for a french 42 or a 9 UK; this usually translates to an 11 in the US as far as I know.
However, some Amazon shoes & boots have both a 9 and a "9 US" listed as available sizes. Are these the same or different sizes? I'm interpreting this as a "9 UK" and a "9 US", i.e. different sizes. Am I right? If so, I could broaden my research and consider the 9 UK ones as well as the 11's .
Any advice is appreciated.