The differences stem primarily from the different purpose of the model: here, features are not meant to decide how to reorder the sentence, but instead how to bracket the sentence hierarchically so that it can be reordered.
terminal spans have features on the sequence of POS tags and word clusters they contain, while a split non-terminal (k, m, ) is scored based on the tags/clusters of the following words and word pairs: e k , e m−1 , e m , e −1 , (e k , e m ), (e k , e −1 ), and (e m−1 , e m ).