In preparation for minting the first Washington quarter proofs, the original reverse design was reworked to strengthen certain aspects of the reverse design. This was the first ever design change for the reverse of the Washington quarter and it created what we call the B reverse type or variety.
In preaparation for the switch to cupro-nickel clad coinage, the U.S. Mint changed the reverse design for the Washington Quarter. This design is found on most 1965 washignton quarters. AKA the Type C reverse design, and simmilar to the Type B reverse, the arrowheads and leaves directly to the left of the arrowheads on the reverse were given a higher relief and much sharper detail.