This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
from my point of view a system architect mainly has to care about infrastructure and server components and their relationships and connections ( Machines + Network + OS + Serversystems ).
an application architect has to care about the application components and their relationships and their distribution (right decomposition of an application into components + using patterns + building prototypes + place components along the existing infrastructure)
actually, these both skills overlap in some areas and a cooperation between them is essentail (e.g. for sizing issues).