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Hey James, Good question! First off, Open Site Explorer actually uses Linkscape for its data, so data from the two sources should be the same. I checked it out and it looks like the root domain of www.hydropoolhottubs.com - which is all of the subdomains under *.hydropoolhottubs.com - has 102,418 total links pointing to it, while the subdomain www.hydropoolhottubs.com has 2,805 links pointing to it. This is probably because you have a lot of links pointing to a subdomain other than www, like to the root domain or to retailer.hydropoolhottubs.com. I hope this helps! Let me know if you have any other questions or if I can do more to explain it better. Cheers!