Katakana is mainly used in imported words and onomatopoetic words. The word "マップ" is a imported word so it is written katakana.

When you talk to Japanese people, I think it is better to use the word "地図" because there is a Japanese word "地図" which means "map" and マップ is the reading and writing in Japanese for the English word "map".

I think the 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 "map" is English.

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.