The classification of the "us and them" in the Ukrainian famine is the soviets and the peasants of Ukraine. A particular group of people called kulaks were peasant but gained a large amount of money after the Stolypin reform.
The soviets started to take money away from the kulaks and the peasants started to revolt and have riots and because of this Stalin decided to cut off the food supply to the anti-Soviet Ukrainians.
The Kulaks were angry that their money in which they worked for were taken away from the soviets. Before the famine started the soviet used to shoot those who were rebellion but they found it as insufficient in stopping these riots which made the soviets deliberately kill these peasant by a famine.