Light bulb question -- Daniel Stern?

Went to the Sylvania Web site to see whether XtraVision bulbs are
available for my 300M (they aren't) and looked at the comparison chart
for Standard, XtraVision, Cool Blue, and SilverStar. I was surprised to
see that for a given bulb type (e.g., 9004, 9005, 9006) they quote the
same light output in lumens no matter whether it's a Standard or an
XtraVision! So how come they claim that XtraVision are "brighter"?

MB