The ice world of hoth (system) so it is nameless and we all call it planet hoth.
Same for Dagobah.
Bespin is however bespin.
Not necessarily. Just because no one says Bespin system, it does not mean it isn’t called that.
Every other system/planet is like that. Just as Alderaan and Dantooine.
“Looking for passage to the Alderaan system”
“Alderaan is a peaceful planet…”
“You want another target, a military target, than name the system”
“They’re on Dantooine”
I guess in Star Wars movies, every system has one habitable planet or moon. The planet has a name, and the system is named after it, or it is the planet that is named after the system.
Whatever.
And in case of habitable moons like Yavin and Endor, the moon has no name. It is Yavin 4 or simply the Endor moon.