Raunin er önnur.

• raunin = a noun in the definite singular
• er = the present tense of the verb vera (to be)
• önnur = a word meaning other / another / different, used here as a predicate complement after er

So the structure is basically:

• Subject: raunin
• Verb: er
• Complement: önnur

That is the same basic pattern as English X is Y.

Because Icelandic usually adds the definite article to the end of the noun instead of using a separate word like English the.

• raun = reality, fact, actual situation
• raunin = the reality / the actual situation

So -in here is the feminine singular definite ending.

This is very common in Icelandic. Compare the general idea:

• noun alone = a/an
• noun + article ending = the

The base form is raun.

It is a feminine noun. In this sentence, it appears as raunin, which is the nominative singular definite form.

So:

• raun = base dictionary form
• raunin = the reality / the fact / the actual situation

Because önnur has to agree with raunin in gender, number, and case.

The noun raun is:

• feminine
• singular
• nominative here

So the matching form is önnur.

Compare the nominative singular forms:

• annar = masculine
• önnur = feminine
• annað = neuter

Since raunin is feminine, Icelandic uses önnur.

It behaves a lot like an adjective, because it agrees with the noun, but it is often analyzed as a form of annar (other / another / second), which can function adjectivally or pronominally.

In this sentence, it comes after er and describes what raunin is like, so for a learner it is easiest to think of it as a predicate adjective/complement:

• Raunin er önnur. = Reality is different.

Even though the literal form is closer to another/other, the natural English meaning is often different.

Because Icelandic often uses annar / önnur / annað in places where English would naturally say different.

So although önnur literally looks like another or other, the sentence idiomatically means:

• The reality is different
• The actual situation is different
• Things are actually otherwise

This is a very natural Icelandic way to express contrast between appearance and reality.

It is in the nominative case because it is the subject of the sentence.

In Raunin er önnur:

• raunin = subject → nominative
• er = verb
• önnur = complement, also nominative to match the subject

After the verb vera (to be), Icelandic normally uses a nominative complement in sentences like this.

Because after vera (to be), the complement is usually in the nominative, especially when it identifies or describes the subject.

So both parts line up:

• raunin = nominative feminine singular
• önnur = nominative feminine singular

This is similar to how Icelandic says, in effect, The reality is another/different one, with the complement matching the subject grammatically.

The normal, neutral word order is:

• Raunin er önnur.

That is the most natural order for a simple statement.

You may sometimes see changed word order in poetry, emphasis, or more complex clauses, but for everyday learning, this is the pattern to remember:

• subject + verb + complement

So yes, this sentence is in a very standard Icelandic word order.

A learner-friendly approximation is:

• RAU-nin er ÖN-nur

A few pronunciation notes:

• au in raun- is a diphthong, not pronounced like English aw exactly
• ö in önnur is like a rounded vowel, somewhat similar to the vowel in French peur or German hören, though not identical
• the nn is pronounced clearly as a double consonant

If you are just starting out, the main thing is to notice that önnur does not sound like English other.

Yes. This type of sentence is very natural in Icelandic.

It is especially common in contexts where someone contrasts:

• appearance vs. reality
• what was expected vs. what is true
• what was said vs. what actually happened

So Raunin er önnur has the feeling of:

• But the reality is different
• In fact, the situation is otherwise

It can sound slightly formal or written, but it is still very normal Icelandic.

Sometimes, depending on context, but reality, the actual situation, or the fact of the matter is usually safer.

Raun does not always match English truth exactly. In many contexts it points more to:

• what things are really like
• what turns out to be the case
• reality as opposed to appearance

So in this sentence, the reality is different is often a better guide than the truth is another.

Good question, because English learners often expect a direct equivalent of different.

• annar / önnur / annað often means other, another, or in context different
• öðruvísi more directly means different, in a different way

So:

• Raunin er önnur = The reality is different / otherwise
• Raunin er öðruvísi would also be understandable, but it has a slightly different feel and is not the standard phrasing of this fixed-like expression

In short, Raunin er önnur is the idiomatic version to remember.