Google Adwords tool vs Google Trends/Insights

[the_poet]

I noticed that Adwords tool exact searches sometimes differ (very) much from Insights (or Trends, as they obviously show the same numbers). This sounds quite strange, as they basically do the same thing: providing traffic estimates for a certain keyword. If you compare two or more keywords using both tools, the keyword with the highest number of searches in Adwords, may rank second or third in Insights. Have you ever noticed this? Which one would you trust?