I would say it is largely a historiographical issue, and probably more so at the 'popular understanding' end of things. Just like the Irish famine there are academics arguing for and against the Soviet great famine being a genocide (I'm not keen on the term Holodomor), or even exactly what caused it. So in a way the definition of either as genocide or not might not be cut and dried, but in terms of one is generally assumed to be and one isn't we're talking about the popular conception of that event.

The Soviet famine was highly publicsed for political reasons and meshed well with the Cold War rhetoric and the relatively orthodox 'totalitarian' construct of Soviet history/politics. Basically the idea that nothing could have happened without the leadership wanting it to, on the assumptiong that sought and managed to control everything.

I know less about the historiography of the Irish famine, but in that case the responsible party was a global power and part of the status quo at the time. Britain while now less powerful, remains a part of the status quo and hence the general narrative of the empire's history has tended to skew towards what they said about themselves.

In terms of texts that show different sides of the Soviet famine debate:

• Robert Conquest's 'Harvest of Sorrow' demonstrates the general argument in favour of the famine being inflicted.

• From memory Michael Ellman tends to argue the famine wasn't deliberate as such, but that it could have been aleviated if the state had wanted to (basically by not exporting grain).

• Stephen Wheatcroft and R.W Davies' 'The Years of Hunger' takes the point of view that the famine was more likely the result of bad agrarian policy.

• Mark Tauger has written a number of articles about the famine, with a general argument that weather and crop disease was the tipping point for the famine rather than state action. His piece 'Retrospective for Yale Agrarian Studes' is him outlining his previous arguments and he also indulges the idea that his opponents are still fighting the Cold War.

As always I add the disclaimer that I'm not sure that I agree with Tauger, but he is a good example of how there is room for a lot of work and alternate opinions in the area.