The Dell's wireless is a 802.11g card (so the antenna hangs out and uses up the card slot). The Mac's is 802.11n and is integrated leaving a free card slot.
Oh, and Dell sells this computer for $1900, not $1600.
The specs look close superficially, but dig down and the machines aren't even close in terms of features and performance.
If it's worth doing, it's worth doing for money.