The men's world record in the 400 meter dash is 43.18 seconds. The men's world record in the 400 meter hurdles is 46.78 seconds. This is a difference of 3.60 seconds. The women's world record in the 400 meter dash is 47.60 seconds. The women's world record in the 400 meter hurdles is 52.34 seconds. This is a difference of 4.74 seconds.
Click on the 'Progression of Men's 400 Meter World Record' link on this page to see who has held the men's world record through time in the 400 meter run.
There is no 300 meter swim. There is a 200 and a 400 meter though. So since it doesn't exist there is no record.
The men's 400 meter hurdles world record in 1990 was 47.02 seconds set by Edwin Moses of the United States in 1983.
The world record for the 400 meter dash has been held by Michael Johnson since 1999.
The world record time for a 400 meter swim in a long-course pool is 3 minutes and 40.07 seconds, set by German Paul Biedermann.