Raincoat. A rain coat is specially designed to protect you from the rain. The primary purpose of a jacket is to protect you from the cold.

Hi Sara. We don't say "rainy coat." We say either "raincoat" or "rain jacket." Raincoat and rain jacket usually mean the same thing. However, if you remove "rain" and just say "coat"/"jacket," then a coat is usually heavier than a jacket and it's worn in colder weather.

Raincoat. Maybe longer than a jacket.

"Rainy coat" is incorrect. The word is "raincoat." There is no precise distinction between "coat" and "jacket." A jacket is a short coat. Today the temperature was 9° and I wore a jacket that came down to my waist. When it gets really cold I have a heavy winter coat that comes down almost to my knees.