No big difference between them. In your example, the word 'which' separates the first thought from the 2nd thought. You could use "that" or 'that which' sometimes.

It is a normal phrase to me, but not often used. A quick search reveals grammar websites with it, which have several examples: https://ludwig.guru/s/which+in+turn https://www.powerthesaurus.org/which_in_turn/synonyms https://ell.stackexchange.com/questions/148058/correct-usage-of-which-in-turn https://strategiesforparents.com/which-in-turn-using-this-common-phrase-in-the-proper-context/ I hope this helps. Like any English phrase, or Russian, etc, if you don't like it, or can't pronounce it (like some russian phrases I try to learn), just remember it, know it is there, but use an easier substitute phrase when you talk. When I have a doubt about a new word or phrase, I usually add an explanation of what I am asking about.