Resources are about equal between the two versions, IMO. Freeciv has more whales, but Civ2 has more shielded grassland. As SG[1] pointed out, the auto-settler is painfully stupid in Civ2. Don't use it. If you're playing a straight ICS, why are you irrigating, anyway? My settlers almost never build anything but roads and cities when I'm in ICS mode.
I would point at three things in Freeciv that might account for your faster progress. The tech costs don't increase as fast in Freeciv as in Civ2, so your research goes a lot faster as the game progresses. ICS government progression: Despotism
, Monarchy
, Communism
, Fundamentalism
. Also, Freeciv gives you credit for "overspent" shields. For example, if a city is producing 6 shields, it can build a horseman in 4 turns, with 4 shields left over. In Civ2, those 4 extra shields are lost; in Freeciv, they are credited toward the next build. This reduces the amount of micromanagement you need to perform to optimize your cities' production. Finally, the happiness consequences of having "too many" cities appear to be less severe in Freeciv than in Civ2 (although the black-to-happy bug in Civ2 can offset this problem, or even turn it into an advantage).
In both games, your population will prefer to work on high-food squares. Once a city grows to size 2, I always move my workers off fish and non-shield grassland to something that will produce at least one shield, so the city can produce a settler faster.