Because a picture is worth a thousand words, here are some:
There is no easy way to eliminate search engine activity from the Awstat report. The large “error” makes the report rather useless, in my opinion. Awstats reports nearly 10 times the number of page views that Woopra has. This is not insignificant.
Because Woopra gives me information about each individual visitor, it is possible to reconcile the Woopra numbers against the raw web server logs. This exercise could theoretically provide some insights as to why the Google and Woopra numbers are slightly different. Interestingly enough, they are off in both directions (compare March 10 and March 25, for instance). I don’t have that much time on my hands, unfortunately :-).