WHY KEYWORD RESEARCH TOOLS GIVE SUCH DIFFERENT NUMBERS

Summary from the TLDR Marketing newsletter

Google Keyword Planner (and related tools such as Keywords Everywhere) provide data on the inputted keyword clustered with other similar terms. Ahrefs uses Google Keyword Planner data but attempts to ungroup the keyword clusters and refine search volumes using additional data sources. SEMrush uses its own algorithms to come up with another different number, but often ends up closer to Ahrefs than KWP. Consequently, for the term "Jigsaw Puzzle" you will see 40.5k volume in Google Keyword Planner and 21k volume in Ahrefs.