Answer:
The tree of life refers to a conventional model, which illustrates the origin of Eukaryotes and the relationship amongst the organisms. On the basis of this model, the Archaea and Eukaryotes are the sister lineages, as both descended from the bacterial ancestors.
On the other hand, the ring of life is a present time model on the basis of which, the emergence of Eukaryotes took place due to the combination of two other domains, that is, Eubacteria and Archaea. The ancestors of Eubacteria and Archaea combined their genomes to produce the initial Eukaryote. That is, two distinct branches of the tree of life were combined to produce the ring of life.