When to use hotto vs. atatakai?

Are both these words synonyms or is atatakai used in some instances vs. hotto?

Hotto is a borrowed word (from English -> hot), while atatakai is a Japanese word. They both mean the same thing, however, it is preferable to use Japanese words instead of borrowed ones, so my recommendation would be: atatakai :).

ありがとうございました。

Hello Fred F7さん、 ゴッドさん gave a good explanation so I'll just give you examples. すみません。ホットチョコレートください。 Excuse me. Please give me some hot chocolate. すみません。暖かいお水ください。　 Excuse me. Please give me some warm water.

Thank you Risa-san!

I am a native Japanese speaker, but an old one. When I was a young girl living in Japan, there were no ホットチョコレート. We called it ココア then and ココア was always hot. We don't usually say 暖かいお水, because 暖かいお水 is called お湯. 暖かいお水 sounds a little bit strange to me. 暖かい is used in front of 日本語, such as 暖かい気候、暖かい服装 etc. ホット is used in front of 外来語 such as ホットコーヒー、ホットスポット. All of 外来語 are always written in カタカナ.

Thank you teruyo w.

Teruyo さん、 こんにちは。 You are right. I should have used another example to use 暖かい in that sentence such as tea:暖かいお茶をください。 Thank you for pointing that out!