Everyone has contributed great experience here.
My overall understanding says that the difference is huge when you come to compare analytics and webmasters.
Let me try to categorize it a bit. Google Analytics gives you the following information:
Web-traffic
Visitors
Keywords
Content
Conversions
Google Webmaster Tools reveals how Google sees your site online like:
Crawling Errors
Search Queries
Links
Malware
HTML errors
and lot more things.