What is the difference between хотя and хотя и?

These comments were originally written on Duolingo Russian forum in "What is the difference between хотя and хотя и?" thread.

by Raoul537337

I translated the sentence "It is winter now, even though it is warm outside." with: Сейчас зима, хотя и на улице тепло.

It was marked wrong, the correct answer should be: "Сейчас зима, хотя на улице тепло."

But what is the difference???

 

by Shady_arc

Oh. You would rather say Сейчас зима, хотя на улице и тепло.

First, a few words about хотя и (хоть и). The и is usually separate from хотя/хоть and comes after the first "block" in the second clause. It is before the main statement but after the topic:

• Мы учим английский, хоть китайский и интереснее. = We study English, even though Chinese is more interesting.
• Я сплю, хотя мне и не хочется. = I am sleeping even though I don't feel like it
• Дуо говорит, что ответ неверный, хотя он (и) правильный. = Duo says the answer is wrong, even though it is correct.

On the other hand, there are cases when the part хотя introduces is just one word or one block (like "not a good one"—you cannot put и inside). It lacks topic. In these cases, хоть и can be right next to each other.

• Я сплю, хоть и не хочется. ← "мне" is omitted; there is nowhere else to put "и"
• На улице хорошо, хоть и холодно. = It is nice, though cold, outside. ← not a clause: "cold" is a continuation of the first half's structure
• Вчера совсем не было времени, хоть и нужно было купить чай. = I had absolutely no time yesterday, even though I needed to buy tea.
• Он не отвечал, хотя и прочитал моё сообщение. = He did not reply even though he read my message. Also, "... хотя моё сообщение и прочитал" (somewhat convoluted but also acceptable)

Now, about your wording. Your sentence means "It is winter, even though it is warm outside as well". It is rather inconvenient that И has multiple uses, including "both...and..." structures and "also":

• Холодно было и на улице, и в доме. = It was cold both outside and in the house.
• Я ем и яблоки (тоже). = I eat apples, too (apart from other things).
• Все дома. Дома и моя мама. = Everyone is at home. My mom is at home as well.