Difference between In the blinking of an eye and Without blinking an eye

in the blinking of an eye—very quickly:

• Mrs. Shaw’s mood changes in the blinking of an eye during an hour long interview—sullen one moment, warm and witty the next.

without blinking an eye—without hesitation or remorse:

• Why is the police chief, a loving family man at home, able to torture a man to the edge of death without blinking an eye?