What's the difference between the kanji term and the katakana term, and when should I use them? I think that some katakana words are only used when the author is being gratuitous with katakana, but I didn't think マップ was one of them.
In case context matters, I'm wanting to talk about tourist maps of cities and towns at a scale small enough to indicate individual landmarks.
The far more versatile choice is 「[地図]{ちず}」; No question about it. I would say that an average native speaker would learn to use 「マップ」 a good 10 years after learning to use 「ちず」 as a toddler.
In school, the word used is 「地図」 virtually 100% of the time and that is both in and outside of geography classes. In daily life, when you draw a simple map to show another person the direction to a place, that map is called 「地図」, but never ever「マップ」. Your collection of maps that you keep in your house or car are called 「地図」.
「マップ」 is most often, if not exclusively, used in proper nouns (as in 「グーグル・マップ」) and in naming little maps created for particular interests for inclusion in magazines, websites, etc. Those include maps of restaurants, maps of clothing stores, etc. in a relatively limited area.
Even when a map is named 「～～マップ」 in a magazine or website, you can still call it a 「地図」 if you want to, but the reverse does not work. You would sound pretty weird if you used 「マップ」 to refer to a map named 「～～地図」 like 「[世界]{せかい}地図」 or 「[東京都]{とうきょうと}地図」.
the official translation of the map app on iOS is マップ, which leads me to think it's only used to denote a specific app whose NAME is マップ; but indeed, when referring to an actual map, and not the app that bares such name, they use 地図.
Katakana is mainly used in imported words and onomatopoetic words. The word "マップ" is a imported word so it is written katakana.
I think the basic difference in usage is 地図 is mainly used in Japan and マップ is mainly used for foreign people because 地図 is Japanese and マップ is the reading and writing in Japanese for the English word "map".
In addition, we eager to use English words in many situations like even Japanese news. I think many Japanese may think using English words is cool. When we use the word "マップ”、this may be a main reason.
