Learn Hardcore Russian: Этот маршрут короче, чем тот.

In Russian, the verb быть (to be) is normally omitted in the present tense in simple sentences like this.
So instead of literally saying Этот маршрут есть короче, чем тот, Russian just says Этот маршрут короче, чем тот.
Learners usually supply the “is” in English when translating, but in Russian it’s understood from context and the structure of the sentence.

What is the grammatical case of этот маршрут and тот, and why?

Both этот маршрут and тот are in the nominative case.
In a comparison like this, you are essentially saying:

Этот маршрут (есть) короче, чем тот (маршрут).

Both things being compared are treated like subjects or subject-like elements, so they stay in the nominative. Nothing here requires an object case (like accusative or genitive).

Why этот маршрут and not это маршрут?

этот маршрут = “this route” as a noun phrase (adjective + noun).
это маршрут = “this is a route” (identification sentence using это).

In our sentence, “this route” is the subject being described as shorter, so we need the demonstrative adjective этот to agree with the masculine noun маршрут.
это маршрут короче, чем тот would be ungrammatical.

What is короче grammatically? How is it formed?

короче is the comparative form of the adjective короткий (short).
Russian often forms comparatives by changing the adjective’s ending instead of adding an extra word:

короткий → короче (short → shorter)
длинный → длиннее (long → longer)

So Этот маршрут короче, чем тот literally means “This route is shorter than that (one).”

Could I say более короткий instead of короче? What is the difference?

Yes, you can say Этот маршрут более короткий, чем тот, and it is grammatically correct.

However:

короче is the normal, most natural form in everyday speech.
более короткий sounds more formal, heavy, or emphatic, and with common adjectives like короткий, native speakers almost always prefer короче.

So learn and use короче as your default.

Why is there a comma before чем? Can I drop it?

In school-style and careful written Russian, a comma is usually written before чем in simple comparisons:

Этот маршрут короче, чем тот.

In modern usage, especially in short, simple comparisons, the comma can often be omitted:

Этот маршрут короче чем тот.

Both versions are acceptable; as a learner, it’s safer to keep the comma, because it is always correct in this kind of structure.

Why do we use чем here and not как?

For straightforward adjective/adverb comparatives like “shorter than X”, Russian normally uses чем:

короче, чем тот
быстрее, чем вчера

как is typically used in equality constructions:

такой же короткий, как тот – as short as that one

So короче, как тот is not correct for a basic “shorter than that one” comparison.

Why is it just чем тот, not чем тот маршрут?

Russian often avoids repeating the same noun if it’s clear from context.
Here, тот clearly refers to тот маршрут, so speakers normally drop the repeated noun:

Full: Этот маршрут короче, чем тот маршрут.
Natural: Этот маршрут короче, чем тот.

Both are correct, but the shorter version sounds more natural.

Could I say Этот маршрут короче того instead of … чем тот? Is there a difference?

Yes, you can also say:

Этот маршрут короче того.

Here того is genitive (того маршрута) and there is no “чем”. This is another standard way to form a comparison in Russian.

Nuance:

короче, чем тот – very common, neutral.
короче того – a bit more compact; can sound slightly more bookish or stylistic, but is fully normal.

As a learner, you can safely stick to короче, чем…, then later add the genitive pattern.

What is the stress and pronunciation of each word in this sentence?

Этот – Э́тот (stress on the first syllable: Э́-тот)
маршрут – маршу́т (stress on -шрут)
короче – коро́че (stress on -ро́-)
чем – чем (one syllable, like chem with a soft ч)
тот – тот (like English tote but shorter; hard т sound)

Entire sentence: Э́тот маршру́т коро́че, чем тот.

What gender is маршрут, and how does that affect the sentence?

маршрут is masculine. You can see that from:

the demonstrative этот (masculine form; feminine would be эта, neuter это)

The gender of маршрут controls the form of words that agree with it (like этот).
The comparative короче does not change for gender, so it stays the same for маршрут, дорога, etc.

Could I change the word order, for example: Маршрут этот короче, чем тот? Is that okay?

Yes, Russian allows some flexibility in word order. For example:

Маршрут этот короче, чем тот. – also correct; slightly different emphasis (you’re foregrounding маршрут).
Короче этот маршрут, чем тот. – possible, but sounds more poetic or expressive.

However, something like Этот маршрут тот короче is wrong; you still need the basic structure: [subject] [comparative] (чем [comparison]).