They belong to two different language families. Farsi is a Indo-European language and belongs to the Indo-Iranian branch of this language family. Arabic belongs to the Semitic branch of the Afrosiatic language family.

It is like russian and ukrainian... they seem the same but they are not!!!

I was surprised the first time that I heard from foreigners that they think Arabic and Farsi are almost a same language. It took me a while to convince my American friend that we don't speak Arabic here in Iran. Sometimes they even use Arab actrors for Persian characters in the movies. But in fact I think you'd better to ask what are the similarities between Persian and Arabic? Because these are two different languages which have some things in common. Like the alphabet. European languages use the same latin script but we know French and German are not same, neither Arabic and Persian. Also there are many words with the same root in Persian and Arabic, but still they are way different.

Well, it's absolutely different from each other. In Iran we have some Arabic courses in 3 years of high school and a lot of Iranian people including me can not speak Arabic and those courses are not high level Arabic courses( whereas some religious Iranian know a little more Arabic since it's the language of Quran.) Totally different languages. It's somehow the alphabets are the same( some pronunciation of them are different) and Persian language has 4 more alphabets than Arabic. I hope I could help you with that. :)

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