similar lumens, but people need to realize that the sun gives off spectrums in phases, it's not always red, its not always blue, its mixtures of the two in different levels, + radiation that is unique only to the sun. I mean you can only match so many things on a nuclear fusion ball in space 50x+ bigger than earth...
and I hypothesize that there are other aspects to the sun that change the bud too that science isn't aware of. if you notice indoor bud has elongated trichomes, aprox 2-4x longer than that of outdoor. there are often more trichomes but if its done correctly with the right strain outside it will be just as crystally.
indoor has the illusion of being more crystally because of the elongated trichomes, outdoor has short and stout trichomes, all the cannabinoids are in the head of the trichome, much less in the stalks, so I think because outdoor has larger heads to the trichomes but shorter stalks that indicates something the sun is doing, and the differences in the duration and acute intensities of the high.