The Cost Analysis section allows you to measure sessions, costs and revenue performance for paid advertising campaigns. You can connect your Google Analytics to Google AdWords to see AdWords reporting, or upload data from other advertising sources.
Acquisition report let visitors know from where people are finding your website. You get to know traffic sources from reporting section under Acquisitions.
You can use Acquisition Reports to compare the performance of different marketing channels and discover which sources send you the highest-quality traffic and conversions. This can help you make better decisions about where to focus your marketing efforts. Acquisition Reports are under Acquisition in the left-hand navigation.