Whereas planet 1 focused on short-vowel sounds only within words that followed a consonant-vowel-consonant pattern, planet 2 moves on to more complex consonant blends (where you hear separate sounds for each consonant) and digraphs (where the consonants work together to make one new sound).
This level focuses on consonant blends where the second letter is an R. Words that start with br, dr, fr, gr, and tr are all included in these ten words.
An interesting teaching point in this level is that the words frog and from are rule-breakers: the letter o doesn't make a short-vowel sound anymore -- and it isn't even the same in each of those two words, either!