The 4 years experience OR 1,000 hours applies to two different scenarios.

If your credentials were earned in the USA, you must have 4 years experience. However, if you are a foreign-trade nurse, medical doctor, etc. (i.e. the equivalent), then you may apply with only 1,000 qualifiable hours.

The 1,000 hours are the equivalent of the 4 years work experience for qualified (foreign-trained) doctors, nurses, etc. whom are licensed in their countries of origin but cannot practice in the USA.