Kelvin was developed from Celsius. The only difference is that 0° is based on absolute 0 (because it's logical and constant) rather than the rough freezing point of water (a vague and inconsistent reference point). Every degree change in one unit is exactly the same change in the other.

Ehh, they were developed in different ways using completely different reference points

Ah yes just rolls off the tongue. Totally the same as, an increment of one is equal in both.

In that case I assume it would be 0 Rankine without degrees, too? Because it's an absolute unit like Kelvin.