What are the variations between countries? I know that Holland accrues interest on gold in the colonies. That is all I got! Help!

From the manual:

Britain: Playing as this country gives you the bonuses equivalent to those you (your Ships)
would get if you had chosen the Admiral special ability. You can still choose the Admiral
ability when playing as Britain. You will then get a double bonus. Your Artillery units
receive improved defensive and offensive skills equivalent to 1 plus the ratings of Artillery
offense and defense accrued through your War College.

France: Playing as France improves your starting relations with the native Indians in the
New World (by 30 points on a 201-point scale). In addition, Cavalry units receive
bonuses to their defensive and offensive skills equivalent to 1 plus your War College’s
ratings in Cavalry offense and defense.

High Natives: In addition to the basic differences between playing as native Indians
and playing as Europeans detailed elsewhere in this manual, High Natives receive
some specific bonuses. All land units move as if they were one level higher than they
are (i.e., they can move farther per level than European units can). Native players’
Gold Mines will always be able to produce some Gold. Unlike those of European
players’, whose Gold Mines may be useless because productivity modifiers can go as
low as -100%, Native players’ Gold Mines always have productivity modifiers greater
than or equal to -90%. Native players’ Gold Mines also produce more Gold per level
than those of European players. Finally, Cavalry units receive bonuses to their
defensive and offensive skills equivalent to 1 plus your War College ratings in these
areas.

Holland: Playing as Holland has some truly unique benefits. Your Gold stockpiles
(in all colonies) accrue interest—at a rate of 5% per game turn! Furthermore, all
trades that Holland players conduct with their Mother Country take one fewer turns
to complete; although a trade always takes at least one turn. Holland receives no
military benefits.

Portugal: Portuguese units move as if you were playing at a game setting that is one
easier than it actually is. For example, if you have set the game to Normal movement,
Portuguese units will move as if you had set it to Easy movement. This allows them
to move an additional 50% per turn! The Portuguese get no military benefits.

Spain: If you play as Spain, your Explorers will act as if they are one level higher than
they actually are—i.e., they can move farther per turn. Your Infantry units also
receive a bonus to their defensive and offensive skill equivalent to adding 1 to your
War College ratings in these areas.

Cheers,