Hi Cherie,
Yes and No in that order, for your two questions above.
Not that I have used CS4, but one is just a cut down version of the other.
The picture viewing bit in Elements is replaced by something called "Bridge" in CS2/3/4.
Whereas Elements is just "Elements" or occasionally "Elements (Editor)" when viewed as the right click "Open with..." dialog in Windows file explorer.
Cheers,