As far as I know the only difference is the age of the detectors and difference in the stickers. The Spectrum XLT is what White's called the first XLT's, it seems they've dropped the Spectrum part now for some reason? Of course, the newer detectors probably have newer (upgraded?) microchips in them too. I know my Spectrum XLT doesn't use those cheesy icons they use now. Good question... You may want to call White's and ask them just to be sure...