A snake which was eating frog in a dream means that your sexual desires is taking over spiritual interest. Also, it can mean that you have been receiving a lot of passion toward some person that you have met recently. Alternatively, if a snake has finished eating of a frog in a dream, then it symbolizes forthcoming financial gains, that will be reached by using a lot of energy.
A frog that was eating snake in a dream means that your sexual interest is being taken over by spiritual desires. Also, such dream can denote that recently you have received a lot of passionate interest from some person, which is not an old friend. On other hand, if a frog successfully ate a snake, such dream means easily obtained wealth in near future.