Answer:
Savannas have a fairly constant temperature all year; temperate grasslands have a greater seasonal temperature variation.
Explanation:
For example, the African Savanna has an almost constant temperature all year (see the first figure below).
The difference between summer and winter temperatures is only about 5 °C, and the rate of temperature change is quite slow.
The temperature of a temperate grassland (see the second figure below) has a much greater seasonal variation.
The summers are hot, and the winters are cold. The difference between summer and winter temperatures is about 30 °C, with a rapid rate of temperature change from one season to the next.