There are some important differences, and the subjectivity of human judgement is a major one. Also, compression is an interesting goal in its own right. But if

There are some important differences, and the subjectivity of human judgement is a major one. Also, compression is an interesting goal in its own right. But if the Hutter Prize is proposed as a way of encouraging AI research then I still claim that some of the criticism of the Loebner Prize is applicable. To me it seems doubtful whether compression of a 1 GB text corpus could benefit from AI even in theory: if you can get it down to about 15 MB without AI then any AI would have a very tight budget. Perhaps compression of a 1 TB text corpus could benefit from AI in theory, but that doesn't mean that people working on AI would have much chance of winning the prize in the foreseeable future because there might be lots of non-AI techniques that provide a bigger improvement in the short or medium term. (A similar criticism was made against the Loebner Prize in the 1990s. Sorry I can't immediately find a link to it.)