In May 1941, the United States Treasury introduced the new Series E bonds as Defense Savings Bonds. After the American entry into WWII the title of the bonds was changed to War Savings Bonds.
Series E Defense Bonds were issued in denominations of $25.00, $50.00, $100.00, $500.00 and $1,000.00.
The first Defense Bonds printed by the BEP were given the nomenclature of New Design. This carried forward the BEP nomenclature from Series D bonds. The New Design type of Defense Bond.
The identifying characteristic of the New Design type Defense Bond is the perforations where the bond was held in place in the bond booklet are at the top.
Here is an example of the New Design type $25.00 Defense Bond.

And a close up of the top perforations.

The frame is also a slightly different size compared to the later type. The serial number range for the New Design type of $25.00 Defense Bond is from 1-4,595,000 (approx.).