Learn Hardcore Russian: Модель этой рубашки отличается от предыдущей. - The design of this shirt differs from the previous one.

этой is the genitive singular feminine form of этот, and рубашки is the genitive singular of рубашка. The genitive case here expresses a possessive/attributive relationship: модель (чего?) этой рубашки – “model of this shirt.”

Why is the verb отличается reflexive, and what does it mean?

отличаться includes the reflexive suffix -ся and means “to differ” (imperfective). Don’t confuse it with отличать (“to distinguish”). отличаться requires от + genitive to mark what you’re comparing against.

Which case follows the preposition от, and how is предыдущий declined for it?

от governs the genitive case. The adjective предыдущий in genitive feminine singular becomes предыдущей, agreeing with the implied noun модель (feminine).

Why is предыдущей used without a noun, and what noun is implied?

Russian often lets adjectives (and pronouns) stand alone when the noun is clear from context. Here предыдущей substitutes for предыдущей модели, with модель understood from the first clause.

How is предыдущей pronounced, and where is the stress?

It’s pronounced [prʲɪdʊˈduɕːej], with stress on the ду syllable: при-ДУ-щей.

Can you omit этой and say Модель рубашки отличается от предыдущей? How does the meaning change?

Yes. Omitting этой makes it more general: “The shirt’s model differs from the previous one.” You simply lose the emphasis on this specific shirt, but the core meaning stays the same.

Why is there no article like the or a in Russian before модель?

Russian has no articles. Definiteness or indefiniteness is inferred from context or added with demonstratives like этой, instead of separate words for “the” or “a.”

How else could you express the same idea in Russian using a different construction?

For example: У этой рубашки другая модель, чем у предыдущей.
Literally “This shirt has a different model than the previous one,” using у + genitive and чем (“than”).

Could you start the sentence with От предыдущей? What would that look like?

Yes, for emphasis on the contrast you can front the phrase:
От предыдущей модель этой рубашки отличается.
This inversion highlights the difference.

What is the perfective form of отличаться, and how does its meaning differ?

The perfective counterpart is отличиться. Besides “to differ” in a single completed action, it often means “to stand out” or “to distinguish oneself,” e.g. Он отличился в конкурсе – “He distinguished himself in the competition.”