SEO Traffic measures the number of visits to your website resulting from organic search traffic via search engines like Google, Bing, Yahoo, etc...
SeoLabs Traffic data are estimations from our data on keywords and search per month of those keywords
By combining web visit metrics with goal achievement metrics, you get a complete picture of your SEO performance. Too often, search engine optimization is treated as a separate initiative, when in fact it should be considered in the context of your website's performance and your overall marketing efforts.
SEO traffic is an important metric, of course, but it's even more important to capture all aspects of it: Brand vs. non-brand, money pages vs. blog, homepage vs. deep pages…etc. The more precisely you define your goal, the better you can measure it accurately.