So Boerd said
Spain can project more power than Portugal?
Yes
Pasta Sentient said
How are tiers determined? Like I agree that historically some nations have more of an imprint than others, but whether a nation is Tier 3 or Tier 2 could be a matter of opinion as opposed to factual.
How is the projection power determined? What stats are being used to determine the the tier system? Or is it just opinion?
Arbitrarily. I'll try to explain the tiers.
Tier I is filled by the world's top dogs. Britain and France with their strong position in Europe and massive colonial empire, rising star Germany that aims to compete with and outshine the former two, and the Russian giant covering 1/6th of the world's land area. These nations are the most relevant.
Tier II: Consists of nations that could, in terms of strength, give Tier I a run for its money, especially the USA. However, they aren't quite as strong as the top dogs and/or they fail to leave a mark that's suitable for a world power.
Tier III: Medium/Regional powers. These countries hover between II and IV. They can't possibly face a Tier I or Tier II nation alone, but because of their power projection and colonial empire (Netherlands now), still being stronger than average (Spain), or being a regional giant (Brazil) gives them a position that's still above average. Despite being an unciv, China is here too since it's fucking massive.
Tier IV: The Joe Average nations. They mainly just sit there minding their own business, and any imprint they want to leave in foreign affairs will be through working together with others or by shady business. Could make convenient allies.
Tier V: Uncivilised nations and/or nations that do not control their foreign affairs.
Pepperm1nts said
But I imagine that being active on the world stage would help too. Even if it's just getting involved in international topics.
This is 100% correct. It is the reason the US is not a Tier I.