A thumbnail understanding of Google AdWords and Facebook ads and promoted posts:
Google Adwords: comparable to the yellow pages or classified ads
Google Adwords is search-based. Users are looking for your service or product and AdWords puts you in their search results. The more you are willing to pay per click, the higher you’ll appear in the results. Adwords offers keyword targeting, and allows you to target by location. It also offers negative keywords for excluding clicks that you do not want.
Facebook: comparable to television and radio ads
Facebook ads and promoted posts are like mass media—newspapers, television and radio. Use Facebook for upcoming events, to make your brand known, or to promote a candidate or ballot measure. Facebook allows you to target users based on location and demographics, but you are competing for attention in users’ newsfeed.