There is a distinction there. In fact the original team wanted to use "I don't want to set the world on fire"... but they wanted too much money to license it. They found Maybe in the back catalog, and discovered that it worked even better. Its theme was about someone missing the singer (the old world) when they were gone.
Fallout uses Maybe in the title, as a remembrance of the old world as it was... but for the rest of the game—all of the music that accompanies the world as it is... is not of old word. It actually is linked with the locations and cultures the player finds. They commissioned this music; they actually got flak from their marketing department for this music... They were questioned about how depressing it sounded—and they assured them that it was deliberate; the whole world is dead in the game. They could have just as easily commissioned 50's style music—rather than license more tunes... had that been their intention for the music.