Why would a war be known by two different names?

Answer 1

Opposing sides typically have different names for wars, battles, and such. For example, the American Civil War was often known as the War of Northern Aggression by Southerners, they had different ways of naming battles.

Sometimes, it has to do with political ideology. The Finns saw their fight against the Soviet Union as a continuation of the Winter War they had previously fought against the Soviets, whereas the Soviets considered it just another front of the Great Patriotic War (their name for the Second World War).