Final answer:
Interval scales are similar to ordinal scales, but the key difference is that the equal intervals can be measured.
Step-by-step explanation:
Interval scales are similar to ordinal scales in that they have a definite ordering. However, the key difference is that on an interval scale, the equal intervals between points can be measured. This means that the differences between the data points have meaning, but there is no starting point and ratios cannot be calculated.
An example of interval scale data is temperature measured in degrees Celsius or Fahrenheit.