The orthologues page allows you to view homologues across different species (Figure 15).
Figure 15. divides homologs into different taxonomic groups.
Select a taxonomic group in the table on the orthologues page to reveal genes in the group. A separate paralogues view shows homologues within the same species. Orthologues and paralogues are determined using a representative protein for every gene in Ensembl, and comparing them in a phylogenetic tree. See this article for more.