Every colonizable space body has 4 digit index close to its type title, representing [population civil tactical health] max upgrades allowed.
The same upgrade level provides the same effect for every planet.
All Stellar & Planetary bodies are physically enlarged.
Planetary bodies are divided into few major classes by size: Gas Giants (uncolonizable), Planets, Planetoids, Dwarfs, Asteroids (uncolonizable).
Introduced planet types are based on scientific background.
Planets are more valuable, have good stats and easier to protect but require abundant investments. Planetoids have quite poor stats.
Social, Industry & Smuggling specializations have one stage only with major impact, depending on a planet type.
Interstellar hyperspace speed has been reduced, so stellar distance is important to consider.