The main difference between branding and performance is the difference in goal and measurability.
For branding, it is important that your consumers know about your brand or product, as well as that they are familiar with your brand, your look & feel and your image. In general, you are creating awareness. Branding and awareness are more difficult to measure than a performance-driven goal, such as a click, lead or acquisition. Branding is mainly the measurement via brand science surveys, in which the reached audiences receive a questionnaire about the brand. Another important metric for branding is viewability.
Performance marketing is driven by measurable metrics, such as the amount of clicks, generated leads or realized acquisitions. This can easily be measured with the right set-up and a good analytic structure.