Are you asking about the different tile types that the terraforming improvements can affect, or are you asking about something else?
- The Planetary Soil Upgrade, Soil Engineering, and the Utra Terraformer can all be built upon any tile with at least 30% land area
- The Terraforming Plant can be built upon any tile with at least 25% land area
- Habitat Improvement can be built upon any tile with at least 20% land area
- Resequencing Stations can be built upon any tile with at least 15% land area
- Biosphere Manipulators can be built upon any tile with at least 35% land area
- Biospheres and Universal Soil Adapters can be built on any tile.
Ultra Terraformers are the only one of these which are not colony-unique, and cost more to build than Planetary Soil Upgrades or Soil Engineering (but less than Biosphere Manipulators, which are worse, so if you can obtain both there's no reason I can see to ever use Biosphere Manipulators except to avoid waiting). There's unfortunately no way to see how much 'land area' a tile has except as a best-guess by looking at the planet surface view (and for judging the difference between 15%, 20%, 25%, and 30%, well, let's just not get our hopes too high), so in my opinion it's best to wait to undertake any terraforming projects except maybe the PSU and SE until you unlock the Ultra Terraformer so as to avoid wasting a shot at upgrading an additional tile. (Why wait rather than compare what the PSU/SE can upgrade with what the others can upgrade? Because it's a pain to remember where all the tiles that you can or cannot affect are.)
If you are instead looking for what effect the +X levels to adjacent (type) improvements, then the exact effect can vary depending on the improvement used, but improvements generally offer +5% per level to whatever the basic building of their type boosts (so a culture building will probably offer +5% influence generation per level, a factory will generally offer +5% manufacturing, and so on); levels to the wrong type do nothing, and tiles that offer a bonus do nothing if you don't build the right kind of improvement to take advantage of the bonus offered. Note that taking advantage of the bonus offered is not necessarily advisable; you will generally be better off specializing your worlds to produce one output type than you will be if you mix improvements to 'take advantage' of the bonuses offered by the tiles.
If you were looking for something else, I'm afraid you're going to need to be more specific with your question.
