The Authoritas spider follows similar methodology to Googlebot, to crawl all the pages on your website.  The amount of data and depth of data shown by Google in Google Webmaster Tools will differ from the Authoritas crawler.
But the Authoritas crawler will also merge the website crawl data with other useful metrics from Google or Adobe analytics, backlink data from Majestic and Authoritas ranking data to give you far more actionable advice.
Oh, and of course you cannot crawl competitors’ websites using Googlebot!