Without getting into detail, there are basically two methods of making beer, top down fermentation and bottom up fermentation, lager being the latter - and this depends on the type of yeast used. Apart from that, the only difference between them really is the amount the cereals are toasted and the amount of hops applied. After that it's all about the gas mix or lack of at the serving point.
I would guess that this is Guinness, but with toasted rather than burnt barley.