kekka ha yosou to tigatta.

は marks 結果 as the topic: as for the result...

So the sentence is presenting information about the result and then saying what was true about it.

• 結果は予想と違った。 = As for the result, it was different from the prediction/expectation.

Using は often gives a natural topic-comment structure in Japanese.

Here, と marks the thing being compared against.

With 違う, A は B と違う means A is different from B.

So:

• 結果は予想と違った。
• The result was different from the expectation.

This と is not an and here. It is the particle used with 違う to show what something differs from.

違った is the plain past form of 違う.

• dictionary form: 違う
• past plain form: 違った
• polite past form: 違いました

So the sentence is using casual/plain style.

違う is a verb, not an adjective.

More specifically, it is a godan verb. That is why it conjugates like this:

• 違う
• 違わない
• 違った
• 違います

English learners sometimes expect something like different to behave like an adjective, but in Japanese 違う behaves as a verb meaning to differ / to be different.

That is why 違った by itself can finish the sentence. It does not need だ after it.

Because 違った says that the result turned out to be different.

In many situations, the speaker is talking about an event whose outcome is now known, so past tense is natural:

• expectation existed
• result came out
• result was different

If you used the non-past:

• 結果は予想と違う。

it would sound more like a general or immediate statement: The result is different from what was expected.

Both are possible, but 違った fits very naturally when talking about an outcome after the fact.

Yes, 結果が予想と違った。 is possible, but the nuance changes.

• 結果は予想と違った。
  Topic-focused: As for the result, it was different from expectations.

• 結果が予想と違った。
  Subject-focused: It was the result that differed from expectations / the result was what differed.

In many contexts, は sounds more natural if you are simply talking about the result as your topic.

Because 違った is already a fully conjugated verb form.

You add だ after nouns and na-adjectives when needed, but not after a verb:

• noun: 学生だ
• na-adjective: 静かだ
• verb: 違った ← already complete

So 違っただ would be wrong.

予想とは違った adds は after と, which creates extra contrast or emphasis.

• 予想と違った = simply was different from expectations
• 予想とは違った = was different from expectations, at least / was not what had been expected

The version without は is more neutral.
The version with とは can sound more contrastive or a bit more emphatic.

Japanese nouns usually do not show singular/plural the way English does.

So 予想 could mean:

• the expectation
• the prediction
• expectations
• predictions

Context tells you which is meant.

This is very common in Japanese. The language often leaves number unspecified unless it really matters.

The polite version is:

• 結果は予想と違いました。

This uses the polite past form 違いました instead of the plain past 違った.

So:

• plain: 結果は予想と違った。
• polite: 結果は予想と違いました。

The meaning is the same; only the level of politeness changes.