Astronomic difference between keyword research tools. WHY?

Hi everybody!

Thank you for your answers,

Question: I have reviewed some keyword research tools, and saw a great difference between them. For example Wordtracker gives for "interesting facts" – 44077 daily searches, while Trellian’s Keyword Discovery tool says that it is 114. How it can be?

We all know that no keyword research tool has accurate numbers, but why they have so big differences?

Thanks,
Vusal

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