Hard to believe there is that much of a price difference - are you sure they are the same size, regular vs. HO, number of lumens? (and for the benefit of other readers, that's 6500K.)
You would need to actually do a lot of digging to find the actual light spectrum outputs. I am sure they will differ - but how much and does it really matter?
In the end, I am sure you will find that the expensive ones are better. Do you want a good, vigorous, healthy lawn or the best lawn on the block? That kind of thing. But if there is a difference in lumen output, that will make a big difference.
