Learn Hardcore Russian: Точка зрения моего брата отличается от моей, но это не мешает нам дружить. - My brother’s point of view is different from mine, but that doesn’t stop us from being friends.

If you said точка зрения мой брат, it would be ungrammatical, because мой брат is nominative and cannot directly depend on another noun like that.

Word order:

точка зрения моего брата is the neutral, normal order.
точка зрения брата моего is possible, but sounds more literary or emphatic.

What is моей referring to? Why is the noun not repeated?

Моей is short for моей точки зрения.

Full, “unshortened” version:

Точка зрения моего брата отличается от моей точки зрения…

To avoid repetition, Russian often drops the repeated noun and keeps only the adjective/pronoun that agrees with it:

от моей = from mine (i.e. from my point of view).

Grammatically:

моей is feminine, genitive singular, agreeing with the omitted точки (зрения).
The preposition от requires genitive, so you get от моей.

Why is it отличается от and not some other preposition?

The verb отличаться (to differ, to be different) is normally used with от + genitive:

отличаться от чего? / от кого? – to differ from what / from whom?

So you get:

отличается от моей (точки зрения) – is different from mine.

Using с, из, etc., here would be wrong. This is a fixed government pattern: отличаться от + genitive.

What does the -ся in отличается do?

Отличается is отличать + -ся in 3rd person singular present.

отличать – to distinguish (something from something)
отличаться – to be distinguished, to differ, to be different

The suffix -ся often makes the verb:

reflexive (acting on oneself), or
“middle voice” / intransitive, like to differ, to be seen, etc.

Here it has that middle-voice meaning:

точка зрения моего брата отличается = my brother’s point of view is different.

Why is it отличается от моей, not отличается моей?

Because отличаться takes the preposition от:

отличаться от чего? – to differ from something.

You cannot directly put the noun in instrumental or another case without от in this meaning.
Correct pattern: отличаться от + genitive → от моей (точки зрения).

Why is нам in the dative in это не мешает нам?

The verb мешать (to hinder, to bother, to prevent) takes the dative for the person who is affected:

мешать кому? – to bother / hinder whom? → dative
- мешать мне – to bother me
- мешать тебе – to bother you
- мешать нам – to bother us

So:

это не мешает нам… – this doesn’t prevent us…
нам is dative plural.

Why is дружить in the infinitive: мешать нам дружить?

The common pattern is:

мешать кому? что делать? – to prevent someone from doing something

So you use:

дружить – infinitive (to be friends / to be on friendly terms)

Literally:

это не мешает нам дружить = this does not prevent us from being friends / from maintaining our friendship.

Using a noun like дружбе instead of дружить here would change the structure and not fit the usual verb pattern.

Can I say но это не мешает нам быть друзьями instead of но это не мешает нам дружить?

Yes, that is grammatically correct and natural:

…но это не мешает нам дружить.
…но это не мешает нам быть друзьями.

Both mean almost the same. Nuance:

дружить focuses more on the ongoing activity/state of being friends.
быть друзьями sounds a bit more static: to be friends (as a status).

In everyday speech, дружить is slightly more common and idiomatic in this exact phrase.

What is the difference between точка зрения and мнение?

Both relate to opinions, but there is a nuance:

мнение – opinion in general. Very common, neutral:
- мнение моего брата – my brother’s opinion.
точка зрения – literally point of view, a somewhat more “formal/intellectual” expression. It suggests a perspective, angle, position from which something is viewed:
- точка зрения моего брата – my brother’s point of view (his perspective).

Often they can be interchangeable, but точка зрения can sound a bit more formal or emphasizes the “perspective” aspect.

Why is it это and not оно in но это не мешает нам дружить?

Это here is a demonstrative pronoun referring to the whole situation mentioned before (the difference in points of view).

In Russian:

это often refers to an entire fact, action, or previous clause:
- Он опоздал, и это всех разозлило. – He was late and this made everyone angry.

Similarly:

Точка зрения моего брата отличается от моей, но это не мешает нам дружить.
Это = the fact that our points of view differ.

Оно usually refers to a specific neuter noun (e.g. письмо, место) already mentioned, not an abstract fact.

Why is there a comma before но?

Russian almost always uses a comma before но when it connects two clauses or contrasting parts:

…отличается от моей, но это не мешает нам дружить.

Here we clearly have two clauses:

Точка зрения моего брата отличается от моей
это не мешает нам дружить

They are joined by the conjunction но (but), so a comma is required by standard punctuation rules.

Why is отличается in the present tense? Could we use a different tense?

Отличается is present tense, imperfective aspect.

Here it states a general, ongoing fact:

My brother’s point of view is (in general) different from mine.

You could change the tense if you talk about another time:

отличалась – was different (past)
будет отличаться – will be different (future)

But in this sentence, the idea is timeless / generally true, so the present is most natural.

Is точка зрения treated as one unit grammatically? How does it decline?

Yes, точка зрения is a fixed expression meaning point of view, but grammatically it is still two words:

точка – feminine noun
зрения – genitive singular of зрение (vision, sight)

The whole phrase declines by changing точка, while зрения usually stays in genitive:

nominative: точка зрения
genitive: точки зрения
dative: точке зрения
accusative: точку зрения
instrumental: точкой зрения
prepositional: о точке зрения

In your sentence we have nominative:

Точка зрения моего брата – subject of the sentence.