To be accurate, it wasn’t RADAR that changed the relative night fighting capability...it was the correct EMPLOYMENT and USE of radar that changed that.
We had radar at the Battle of Savo Island in August 1942, and the Japanese had none.
We however, had not the slightest idea on how to employ it and interpret it effectively. Officers either had no idea how to interpret it or were completely uninterested in using it, mistrusting it because they didn’t understand it, which was a more egregious issue. They had developed no effective tactics for its use.
It took Admiral Willis Augustus “Ching” Lee, who came on the scene in the Guadalcanal campaign in the Fall of 1942 to change that, and it was never the same afterwards.
After that, we wouldn’t go to sea without it.