The Samsung Galaxy S Plus is essentially the original Galaxy S with some beefed up internals. It has many of the same aspects as the original. The Galaxy S Plus is an Android 2.3 Gingerbread smartphone topped with the custom TouchWiz 3.0 user interface.
It is powered by a single-core 1.4GHz as opposed to the 1GHz processor found in the original. The Galaxy S Plus features a capacitive 4-inch Super AMOLED display. Another welcomed improvement is the 1650 mAh batter that is found in the Galaxy S Plus. The first Samsung Galaxy S only had a 1500 mAh battery.
source: Engadget Mobile