Learn Hardcore Spanish (Spain): No quiero la verde, sino la roja. - I do not want the green one, but the red one.

Use sino after a negative to correct or replace the first element: “not X, but rather Y.” Here it rejects the green one and substitutes the red one.

No quiero la verde, sino la roja. = I don’t want the green one; rather, the red one. Use pero for a simple contrast or addition, not a replacement:
No quiero la verde, pero puedo mirar otra. = I don’t want the green one, but I can look at another.

When do I use sino vs sino que?

sino + word/phrase (no verb): No quiero la verde, sino la roja.
sino que + finite verb (a full clause): No la quiero verde, sino que la quiero roja. / No quiero la verde, sino que prefiero la roja.

What is the role of la before verde and roja?

It’s the definite article marking that the adjective is acting as a noun (substantivized). It agrees with the omitted feminine noun (e.g., camisa, falda, chaqueta):

Meaning: “the green one” vs “the red one.”

Why is it verde but roja? Shouldn’t both change?

Adjectives in -o change to -a for feminine: rojo → roja. Adjectives ending in -e (like verde) don’t change for gender: el coche verde / la falda verde. Both types change for number: verdes / rojas.

How would this look with masculine or plural nouns?

Masculine singular: No quiero el verde, sino el rojo.
Feminine plural: No quiero las verdes, sino las rojas.
Masculine plural: No quiero los verdes, sino los rojos.

Is the comma before sino required?

It’s common and perfectly correct; many writers include it to mark the contrast. In short sentences it can be omitted:

No quiero la verde, sino la roja.
No quiero la verde sino la roja. Both are acceptable.

Can I drop the article and say No quiero verde, sino roja?

Not in this structure. When an adjective stands in for a noun, Spanish normally needs the article: la verde / la roja. If you use a direct object pronoun, then you can use the adjectives predicatively:

No la quiero verde; la quiero roja.

What noun is being left out?

A specific feminine noun understood from context (e.g., camisa, falda, taza). The article la and the color tell you we’re contrasting two feminine items the speakers can identify.

Could I say this in a positive/alternative way?

Yes:

Quiero la roja, no la verde.
Prefiero la roja a la verde.
Me quedo con la roja.

What’s the difference between sino and si no?

sino (one word) = “but rather,” used after a negative: No quiero la verde, sino la roja.
si no (two words) = “if not”: Si no hay roja, me llevo la verde.

Do all color adjectives behave like this?

Most do and agree in gender/number: rojo/roja/rojos/rojas; negro/negra… Some are invariable for gender (often also for number) like rosa, lila, naranja, violeta when used as adjectives: la camisa rosa / las camisas rosa. As standalone “nouns,” these can be unclear, so speakers often say la de color rosa instead of la rosa (which can mean “the rose”).

Why the definite article (la) and not una?

La points to specific, known options in the situation (e.g., the two shirts we’re looking at). Una would make it generic:

No quiero una verde, sino una roja. = Not a green one (in general), but a red one.

Does sino only work with no?

It typically follows a negative, which can be no or another negative word:

No es verde, sino roja.
No vino nadie, sino María. = Nobody came, but rather María did.

Where is the subject “I” (yo)?

Spanish usually drops subject pronouns because the verb ending shows the subject. (Yo) no quiero… Both are correct; yo is used for emphasis or clarity.

Can I keep the noun instead of using adjectives as nouns?

Yes:

No quiero la camisa verde, sino la camisa roja. More natural Spanish deletes the repeated noun, or uses a pronoun:
No quiero la camisa verde, sino la roja.
No la quiero verde; la quiero roja.

Why not sino a la roja?

sino coordinates equivalents (noun phrases, adjectives, etc.) without a preposition: la verde vs la roja. Use a with comparatives like preferir:

Prefiero la roja a la verde.