Google keyword-research data is unsuitable for Amazon SEO because the two platforms carry different search intent. Google queries are mostly informational — people researching, comparing, learning. Amazon queries are transactional — people who have already decided to buy and are searching to find the specific product.
Because the underlying intent differs, keyword volume, phrasing, and relevance signals from Google tools don't transfer to Amazon; keyword research needs to be sourced from Amazon-specific, transactional search data instead (see Helium 10 Cerebro, Reverse ASIN Lookup (Data Dive)).
Quote: "Google searches are mostly informational... Whereas Amazon searches are transactional. People are searching because they're ready to buy."
Because Amazon search intent is transactional rather than informational, keyword research has to be done with Amazon-specific keyword tools — Helium 10's Helium 10 Cerebro and Helium 10 Magnet (Seed Keyword Expansion), or alternatives such as Sellerize — rather than Google/SEO keyword tools, which are built around informational search volume and don't reflect Amazon conversion behavior. Free keyword tools are called out as inadequate for the same reason: "don't even try using the free keyword tools. You get what you pay for. Garbage in equals garbage out."