"In contrast," could mean being very different from something in the same category that could be thought to be similar, almost shockingly different. For example, "The weather today is very bad in contrast to what the weather was like yesterday." Another example, "My car is driving really good today in contrast to yesterday." "On the contrary," is a statement saying the opposite of what is expected or desiered. For example, "Everyone expected it to be a nice day today, however on the contrary to what we believed it was raining cats and dogs all day long." One last example, "My car is driving really good contrary to what I expected." I hope this has helped a little with your understanding of these phrases. Good luck with your language journey. Chúc may mắn với chuyến đi ngôn ngữ của anh. I hope I said that right. ^_^

"In contrast" indicates that there is a difference between two points. "On the contrary" indicates that there is absolute opposition between two points. "On the contrary" is often used when you disagree with someone i.e. when you take the opposite view. But often differences are not opposites. You can use "in contrast" more widely. "In contrast" is used in more neutral and factual situations. Today, the weather is sunny and warm. In contrast, yesterday the weather was showery and a little cooler than today. (I can't use "on the contrary") I believe that English is an easy language. I have spoken it all my life without problem. On the contrary, many students consider that English is a difficult language. (I could have used "in contrast" here too)