1.
چتور همان نیستند؟ چه کلمه مشترک ترین است؟
چطور همسان نیستند؟ چه کلمهای معمولتر است؟
"Common" has two different meaning in Persian.
a. common = usual (occurring, found, or done often; prevalent) = معمول
b. common = shared by, coming from, or done by two or more people, groups, or things = مشترک
In this question, we should use معمول
2.
فرد ~ individual = a single human being as distinct from a group
It is rarely used in informal conversations.
منفرداً ~ individually
شخص ~ person
It's used in both informal and formal conversations.
شخصیت ~ personality
آدم ~ human - man - guy
It's used in informal conversations frequently.
He's a good guy ~ آدم خوبی است.
3.
صحیح = / = موردعلاقه
These two words have two different meanings.
صحیح ~ correct , right
موردعلاقه ~ favorite , beloved
4.
تفریح ~ سرگرمی
These two words are the same as a noun and used frequently in speeches.
But we use تفریح in verbs : تفریح کردن
سرگرمی کردن is incorrect and we don't have a verb like this.
5.
ناز ~ با مزه ~ با نمک
These three words are the same almost everywhere and used frequently in speeches.
6.
اول = نخست = first
These two words are the same but اول is formal and informal and نخست is just formal.
اولین = نخستین = the first
These two words are the same but اولین is formal and informal and نخستین is just formal.
These words are superlative adjectives.
اول - دوم - سوم - چهارم - پنجم - … ~ first - second - third - fourth - …
اولین - دومین - سومین - چهارمین - پنجمین - … ~ The first, The second, The third, The fourth , The fifth - …