In your language, is there a difference in the word "map" for the two phrases? In English they are the same word, obviously. It always threw me off how in French you can't say "une carte de la ville", you have to say "un plan de la ville". What's the difference? They're both maps! It would be unusual to hear the phrase "city plan" unless you were a professional city planner interested in the various land allocations and zoning of a city.