Soda does require a little different setup than beer, but soda works perfectly fine in a corny (aka: soda) keg, or really any keg actually.
The different setup is---
Soda requires a higher pressure than beer, because soda has a higher carbonation than beer. So typically (made-up numbers here, don't go by them), beer is at 12 psi so it has 2.5 volumes of CO2 (2.5 liters of CO2 per liter of beer, dependent on temperature too.), Soda would be kept at around 30 psi, so it has around 5 volumes of CO2 (5 liters of CO2 per liter of soda). This increase in pressure will cause the soda to foam up like crazy when poured through a beer setup (5-10 feet of serving line). So instead, you need around 30 feet of serving line, to allow for the proper resistance to "slow" down the flow, and prevent foaming. Hope this helps.