Only Neva River has different embankments. Most rivers have one embankment for both sides and for the whole length. Neva river has different embankments not only for the continent and for the islands, but also for the one side. For example, Admiralty Embankment starts at the Palace Bridge and ends at the Decembrists Square, where it becomes the English Embankment.
All in all, Neva river has 22 embankments. You can go through them and not even mention that there are different embankments. However, the most significant monuments stand along this river. Alexander Nevsky Lavra and Smolny Cathedral, Peter's house and Peter and Paul Fortress, the Hermitage and the Admiralty, Senate Square, Bronze Horseman, and St. Isaac's Cathedral.