As a starting point, I took the 3552 sentences referring to Trump but not to any of the other top 7 Republican candidates, and the 1425 sentences referring to Cruz but not any of the others (see the previous post for more detail). I used these to generate the following two word clouds.
These clouds are not uninteresting, but they contain lots of words that don't really set Cruz or Trump apart. In order to home in on those aspects of the coverage, I filtered out all words whose relative frequency in Trump (or Cruz) sentences was not at least twice as high as in sentences about other Republican candidates, as well as in general sentences. This produced the following result:
This is much better. For Trump, we see the centrality of the immigration issue to his campaign — immigrant, border, wall — as well as the focus on his statements: remark, attention, statements, and language are all prominent. For Cruz, meanwhile, we see much more of an emphasis on religion — evangelical, religious, pastor — and on his ideological leaning: conservative is the most prominent word by far, and Tea (Party) shows up too.
In fact, for someone interested in a quick snapshot of the differences between the two candidates, these two wordclouds do a pretty good job. The viscerally negative terms identified in the previous post barely appear, since their frequency is not as high of the more common/neutral words we see here, but even without them it is clear what sets Trump apart.