Robert_Charlton - 12:05 am on Oct 13, 2010 (gmt 0)
For a discussion comparing keyword tools themselves, there's a current discussion that's worth looking at.... [webmasterworld.com...]
In Google Adwords Keyword Tool, It showed the Monthly search of around 3,68,000
In Seobook Keyword Tool - It showed the Monthly search for Google as 61,380.
What were your settings on the Google Tool? Either broad match (rather than exact match) or global monthly volume (worldwide) rather than local monthly volume (ie, within country) could account for the difference.
Not sure where the Seobook Tool gets its data. It may be from Wordtracker, which extrapolates data and tries to project monthly volumes from a small initial sample size. IMO, Google is currently giving the best data.