The separation between the two suburbs is actually along Hampton St, rather than the Nepean. I live in Brighton Beach which is great - half way between walking to Hampton St shops & cafes, or Church St. Also only a short walk to BB Train station and the beach. Both areas are great, but if you like walking - Brighton is definitely the side to be on. Be warned though, there is a constant icy wind across Port Philip bay that makes beach going a bit hit and miss. Most long term residents don't seem to notice it as much, but having moved here only 3 years ago I find it really cold, and it limits my enjoyment of outdoor/beachside activities.
The main difference is the separation of the two by the Nepean Hwy. The village atmosphere in Brighton (Church or Bay Streets) is superior and the close proximity of the beach is also an added factor.
Both are great suburbs, but when money is no object then Brighton draws the crowds.
Matthew Poustie - Property Manager - Hockingstuart Mentone Real Estate