Lightroom Render Intent

Perceptual:
Is good to use if you have alot of bright saturated colours.

Relative:
If “Perceptual” is not the option to use, the “Relative” will produce more accurate prints.

 

Below is an extract from the LR3.2 help library:

Perceptual

Perceptual rendering tries to preserve the visual relationship between colours.
Colours that are in-gamut may change as out-of-gamut colors are shifted to reproducible colours.
Perceptual rendering is a good choice when your image has many out-of gamut colors.

 

Relative

Relative rendering preserves all in-gamut colors and shifts out-of gamut colors to the closest reproducible color.
The Relative option preserves more of the original color and is a good choice when you have few out-of-gamut colors.