Google analytics is free web service from Google to track web visits and statistics of your web site. It will give excellant reports on your site usage, web site content and visitors in charts and graphs.
Google WebMaster tools are free web service from Google for webmasters. Basically it helps webmasters to check indexing status and optimize visibility of their websites.
using these tools webmaster can,
Check and set the crawl rate, and view statistics about how Googlebot accesses a particular site
Generate and check a robots.txt file
List internal and external pages that link to the site
See what keyword searches on Google led to the site being listed in the SERPs, and the click through rates of such listings
View statistics about how Google indexes the site, and if it found any errors while doing it
Set a preferred domain (e.g. prefer "google-page-ranking.blogspot.com" over "www.google-page-ranking.blogspot.com"), which determines how the site url is displayed in SERPs.
