2003 $2 bills were signed by Rosario Marin and John W. Snow.  2003a notes were signed by Anna Escobedo Cabral and John W. Snow.  Besides the A and the signature difference, they are the exact same note.

The United States $2 bill is a current denomination of U.S. currency. Former U.S. President Thomas Jefferson is featured on the obverse of the note. The painting The Declaration of Independence by John Trumbull is featured on the reverse. The design on the obverse (excluding the elements of a Federal Reserve Note) is the oldest design of current U.S. currency, having been adopted in 1929; the reverse is the second oldest design, having been adopted in 1976.