They are the same in physical meaning: all of them are quantities representing the fraction of visible light reflected by a surface.
For general applications, the results are equivalent. For example: 0.50 (50%) of daylight reflectance = 0.50 (50%) of visible light reflectance = 0.50 (50%) of luminous reflectance = 50 of light reflectance value (LRV).
In practice, there are some subtle differences in the test results, due to the different test methods used. Below are the practices implemented in our lab:
- Daylight reflectance: ASTM E903 method is used and a benchtop UV/VIS/NIR spectrophotometer is used;
- Visible light reflectance: NFRC 300, EN 410 or ISO 9050 method is used and a benchtop UV/VIS/NIR spectrophotometer is used;
- Luminous reflectance: AS 1428.1 or AS/NZS 1428.4.1 method is used and a portable spectrophotometer is used
- Light reflectance value: BS 8493 method is used and a portable spectrophotometer is used
Most of the time, the results obtained with different methods are very close (typically less than ±0.01 of variation).