A ratio is a direct comparison of two numbers through division.
For example, imagine a bag has 10 marbles inside of it. 7 of the marbles are red, while the other 3 marbles are blue. The ratio of red to blue can be displayed in several ways:
7 to 3
A rate is a ratio where the two numbers being compared have different units.
Miles per hour(mph) is a rate. An example using this rate would be “150 miles in 4 hours”.
This is a rate because two numbers with different units are being compared. 150 is measured using the unit of “miles”, while 4 is measured using the unit of “hours”.