How does bacteriorhodopsin differ from the rhodopsin present in mammalian eyes?
Although they are similar in both bacteriorhodopsins  and rhodopsins being retinal-binding proteins, the similarity in their amino acid sequence is very limited.

The key difference between them is that rhodopsin is a G-protein-coupled receptor, and this is not the case with bacteriorhodopsin. A quick Google search on Bacteriorhodopsin vs Rhodopsin will send you to a Wikipedia article that says:


  Bacteriorhodopsin belongs to the microbial rhodopsins. They have similarities to vertebrate rhodopsins, the pigments that sense light in the retina. Rhodopsins also contain retinal; however, the functions of rhodopsin and bacteriorhodopsin are different, and there is limited similarity in their amino acid sequences. Both rhodopsin and bacteriorhodopsin belong to the 7TM receptor family of proteins, but rhodopsin is a G protein-coupled receptor and bacteriorhodopsin is not.


A very good paper if you would like to know more about the two is by H. Gobind Khorana on the Two light-transducing membrane proteins.