Both AC and VS offer an enhanced business class product, not first class. The seat arrangement is similar (fully reclining seats in 'pods' arranged in herringbone fashion). AC actually bought the seats from the same manufacturer (which designed them together with VS) but with some differences. The VS bed is considerably more comfortable since the mattress flips over so you are not sleeping on the seat, you are actually on a proper mattress which is quite a bit thicker. I would argue that food and drink are better on VS, as is the attraction of an on-board bar. The flight attendants (male and female) are much more attractive to look at, in case this is important to you. The VS arrivals lounge at LHR is a world away from what AC offers.