Alliance worth more than tech victory?

Difficulty Level:
The base score is based on the intelligence of the various computer players. This makes up the vast majority of the score. There is a slight bonus for playing as the opposite alignment as most of the players for most of the game. It looks at each turn and then looks at how much you are different each turn. But it's a relatively small adustment.

Galaxy Size:
There is a moderate adjustment based on galaxy size. But not much. Gigantic galaxy vs. tiny will be about a 3 to 1 difference in scores if all variables are the same.

Population:
Population is looked at but its value decreases as the game progresses. It is Population P / Turns N ^2. You're actually better off having a pretty good population earlier than having a huge population later and sitting on it. You're not penalized for having long games though, you simply don't get additional points at a certain point. That said, population is a relatively minor part of the scoring. It also takes into account what percentage of the total galactic population you have that turn. That is, your score is then modified by 100% - your percent of the population. So if you have 90% of the galactic population, you're only going to get 10% of the population score that turn.

Technology:
What percentage of the technology tree you have acheived and how fast you get it are added in. A fairly modest bonus but it's still lookeda t.

Economics, Trade Goods, Wonders, etc.
These other things are looked at and a few points added. They won't make that big of a difference (on a 15,000 point score they may add a few hundred points total).

Victory Condition:
Then the victory condition is looked at. The score is multiplied by it. Conquest = 10. Alliance =9. Culture = 8. Technology Victory = 7 (bear in mind that this is partially made up for by having a higher percent of the tech tree completed bonus).

Notes:
You're best scoring scenario is to win but not win too quickly. The system is designed to appeal to the mass majority of players, not the top 10 players. As a result, we want to create a system that rewards people for playing the game as it was designed to be played. That means your best bang for the buck will be games that are medium in length. You get serious diminishing returns. Sitting on 90% of the galaxy for turn after turn is not going to net you more points. You're not penalized either but you're not rewarded for having a huge population if you've got the game wrapped up. On the other hand, win the game in say year 3 due to some specific strategy won't net very good scores because you haven't had time to build up other parts to get multiplied by.