Need help to identify plant

I live next to a shallow lake in southern New Jersey.  During the summer
the lake is covered with lily pads and water lilies.  One water lily has 
a white flower about three inches across and opens fully.  This plant, I 
believe is called a Virginia Water Lily.  The other water lily has a
flower that does not fully open and is about two inches across.  I don't
its common name.  

I need to identify these water lilies with their botanical names.

I appreciate any help you might provide.