A Sequential color scale can be used to represent a range of values that go from low to high or vice versa such as temperature, elevation, or sales. It uses a single hue, varying in saturation or lightness.
A Diverging color scale can be used to highlight the extremes in data by using two different hues that diverge from a central, neutral color. It's useful for emphasizing both high and low values with a clear midpoint e.g. elevation gain/loss, profit/loss, or positive/negative sentiment.
A Qualitative/Categorical color scale can be used when representing distinct categories or groups such as product categories, customer segments, or voting districts. Each category is assigned a different color, and there's no inherent order or magnitude implied.