Zillow has some interesting business model differences to rocket. A small (but I think growing) portion of service they provide is more automated. Eliminating the middleman-realtor type scenario. Rocket is interesting because they have the ability to provide loans and other services Zillow doesn't do. Both are good companies. Other than that they have similar features.
Thought process is RKT is following more conventional practices, and following a similar trajectory as the residential REIT. Zillow taking a more disruptive stance in the industry - has had higher growth so far. Just observation