I feel like I now should elaborate on what difference there is so as to not leave anyone confused.

First of all, I was wrong to advertise Arabic as an Indo-European language. I presumed it to be, but that presumption turned out to be wrong: Arabic belong to a whole different linguistic family, which makes it either non-related (if you follow the more conservative views on language) or very distantly related (if you follow the more liberal/progressive ones) to the other two. As much as it may bother pro-aggressive Jews and Arabs, the Arabic language is of the same origin as Hebrew, which makes the two people more related than they'd like to admit.

Armenian, while an Indo-European language, is most often considered its own branch within the family given how peculiar its development was. That it boasts a unique script helps the case, since the alphabet in question was developed circa 400 AD (for comparison, the Cyrillic script was developed circa 950s AD). Armenian people have a long and deep history which is interesting in itself.

Russian is an Eastern Slavic language, coupled with Ukrainian and Belarussian. Like with all of the three languages, we don't know how old it is, but as I mentioned, the script we now use is a thousand-some years old and was developed by Greek monks from the Byzanthine Empire (with whom, as Russian History lessons tell me, Rus' had rather tight connection, including cultural exchange, shared religion - which is why the script comes to life - and trade).

All of which is to say: the languages are very different, both linguistically and culturally.