I thought it was the easier of the two, because the Civil War's origins are really very complex. You can actually trace the civil war back to the conflict between the optimates and the populares, although that's probably not what they were aiming for.
I assume the differential in the difficulty of the topics was the reason that Pompey was an 'assess' while the Civil War was just 'explain' - to try to level them out a bit.
I thought that the Pompey question was great. Mithridates, Sertorius, Pirates allowed Pompey to step outside the cursus honorum, led to him becoming very high profile very quickly (eg. his consulship, which was totally illegal under the Sullan constitution), raised his dignitas and authoritas substantially, leading to him gaining lots of power in the 60s.