I think it should be fairly easy with a Google search. However in simple terms with AdWords you "pay" for clicks, with AdSense you "get paid" for clicks.
Adwords is a advertising program by google which allows advertisers to advertise their website, blogs or any other web properties through Google search engine and in Google Adsense publisher network sites. And advertiser need to pay Google for each and every click received by their advertisements. Adsense is a ad publisher network by google which allows publisher (website, blog owners) to place advertisements in their websites/blogs (Ads served by Google adwords). And publisher will be getting paid for each and every click* they get on the advertisements in their websites/blogs. *I would recommend any one to review Google adsense policies before proceeding with it.