A way of comparing two related quantities measured in different units, often expressed as a ratio. It indicates how one quantity changes in relation to another, often with respect to time. For instance, speed is a rate that compares distance and time, like kilometres per hour. 

A mathematical way to compare the relative sizes of two or more quantities. It expresses how many times one value contains or is contained within another, often written as a fraction or with a colon (e.g., 2/3 or 2:3). Essentially, ratios show the relationship between different amounts.