Campaign efficiency is measured by --- , and brand awareness is measured by --- .

Campaign efficiency is measured by ACOS (Advertising Cost of Sales), which indicates how much you spend on advertising to generate a certain amount of sales. A lower ACOS generally signifies better efficiency. Brand awareness, on the other hand, is measured by impressions, which represent the number of times your ad was displayed to potential customers. A higher number of impressions indicates broader reach and increased visibility for your brand. ROAS (Return on Ad Spend) is another efficiency metric, similar to ACOS but expressed as a ratio of revenue to ad spend, making it incorrect as a measure of brand awareness. Impressions are not a measure of efficiency, but rather reach.