Question

The difference in temperature between 100°C and 101°C is _____ the difference between 100K and 101K.

Answer 1

The missing word is "equal".

In fact, The relationship between temperature in Celsius and temperature in Kelvin is
$T(^{\circ}C) = T(K)-273.15$
So, the absolute value of the two temperatures are different. However, there is a direct proportionality between the temperature in Celsius and the temperature in Kelvin, this means that temperature differences are equal in both units.

Let's see this with an example: let's call $T_1 (C)$ and $T_2 (C)$ two different temperatures in Celsius, and let's rewrite them in Kelvin using the previous relationship:
$T_2 (C)-T_1 (C) = T_2(K)-273.15-(T_1(K)-273.15) = T_2(K)-T_1(K)$
as we can see, both the 273.15 cancel out and so the temperature difference in Celsius is equal to the temperature difference in Kelvin.