Player can not land their ship on this planet for various reasons.
landable planet ('Landfall' planet)
Player and NPCs can land their ships on this planet.
star
One of starts in current star system.
Horizons 'Planetary port' - small base on planet surface
Player docking permitted. Offers services.
Horizons 'Planetary settlement' - small base on planet surface
Player docking NOT permitted. Usually designated as trespass zone.
They exist as mission targets for Horizons expansion planet surface missions.
Made to be accessed in SRV.
Odyssey 'Planetary settlement' - small base on planet surface
Player docking permitted. Offers services.
Usually does not have underground hangars - landed ships stay on ground. Usually has very limited amount of landing pads; mostly just one.
Part of Odyssey expansion. But accessible in base game (Horizons expansion).
Made for walking around and 'On foot' missions and activities.
Settlement Defense level
Indicates how well is the base defended - how hard it would be attack it both in a ship, SRV and on foot.
Low
Medium
High
Settlement Size
none
1
2
3
4
'Outpost' - small space station, docking permitted, offers services
near this location marker
The marker is displayed at or next to an object that you are nearest to.
From the official Player's guide: "Closest point of interest or the object you are currently in the sphere of influence of."