I am surprised that there is so much contention on this issue. When I bowl lather I work the lather into my beard just as much as I do when I face lather with a shave stick.
I would say that the feeling from building the lather directly on your face compared with just applying it is the difference, it is impossible to work with the finished lather in the same way as with the thick soapy pre-lather. When I bowl lather the brush is filled when I am done in the bowl and when applying it is just slick and soft on the skin, when I apply the dry pre-lather I get more scritch and exfoliation from the brush which are part of the benefits using a brush, at least for me