The fundamental difference
Google Ads captures existing demand. When someone searches 'emergency plumber near me,' they already know they have a problem and they're looking for a solution. Your ad appears at the moment of intent. Facebook Ads create demand. People on Facebook are not looking for your product — they're scrolling. Your ad interrupts them with something relevant enough to make them stop. Both work. But they work at different stages of the customer journey and for different types of products.
When Google Ads wins
Google Ads is typically superior when: your customers are actively searching for what you sell (local services, professional services, products with clear search intent), the purchase decision is made quickly, and your market already knows it needs what you offer. A dentist, a plumber, a lawyer, or a software tool with clear search volume should almost always start with Google Ads. The traffic is more qualified because it comes from people in active buying mode.
When Facebook Ads wins
Facebook Ads is typically superior when: you're selling something people don't know they need yet, you have a highly visual product, you're targeting a specific demographic or interest group, or you're trying to build brand awareness at scale before driving direct response. E-commerce brands, lifestyle products, local events, and businesses with a strong visual identity tend to see better ROI on Facebook. It's also far better for retargeting — showing ads to people who already visited your site.
The cost difference
Google Ads can be expensive because you're bidding for high-intent searches — and so is every competitor. Some industries (legal, insurance, home services) have cost-per-click rates of $10 to $50 or more. Facebook Ads tend to have lower cost-per-click, but lower click quality — the people clicking aren't necessarily in buying mode. Neither is inherently cheaper on a cost-per-customer basis. The right question isn't 'which costs less per click?' It's 'which produces customers at the lowest cost?'
The role of retargeting on both platforms
Both Google and Facebook allow you to show ads to people who have already visited your website. This retargeting is typically the highest-performing ad type on either platform because you're advertising to warm audiences — people who already know you exist. If you're only running prospecting ads (to cold audiences), you're missing the highest-value opportunity. Retargeting campaigns should be part of your strategy on whichever platform you use.
Most established businesses should use both
Google captures people who are already looking. Facebook keeps you top of mind for people who aren't ready yet and recaptures people who visited but didn't convert. Together, they cover the full customer journey. The typical smart approach: start with Google Ads to capture existing demand and prove ROI, then layer in Facebook retargeting to recapture visitors, then expand to Facebook prospecting once you understand your customer acquisition economics.
The real answer: test and measure
The theoretical right answer matters less than the empirical one. For your specific business, your specific offer, and your specific audience, one platform will almost certainly outperform the other. The only way to know is to test both with meaningful budgets, set up proper conversion tracking, and measure cost per customer — not cost per click. Thirty days of honest data will tell you more than any framework.