No quiero la pequeña, sino la grande.

In Spanish, the definite article + adjective can stand in for a noun when the noun is already clear from context.

So:

• la pequeña = the small one
• la grande = the big one

The missing noun is understood, so Spanish does not need to repeat it. This is very common.

For example, if you are talking about camiseta:

• No quiero la camiseta pequeña, sino la grande.
• Or more naturally, once the noun is clear: No quiero la pequeña, sino la grande.

Because the hidden noun is feminine singular.

Spanish adjectives must agree with the noun they describe, even if that noun is omitted.

• la pequeña → feminine singular
• la grande → feminine singular

If the hidden noun were masculine, you would say:

• No quiero el pequeño, sino el grande.

If it were plural:

• No quiero las pequeñas, sino las grandes.

Note that grande has the same form for masculine and feminine in the singular, but it still agrees in number:

• el grande
• la grande
• los grandes
• las grandes

Use sino after a negative statement when you are correcting or replacing one thing with another.

Structure:

• no A, sino B = not A, but rather B

So:

• No quiero la pequeña, sino la grande. = I don’t want the small one, but rather the big one.

Use pero for a general contrast, not for direct correction/replacement.

Compare:

• No quiero la pequeña, sino la grande.
  → not the small one; the big one instead

• No quiero la pequeña, pero es bonita.
  → I don’t want the small one, but it is pretty

That is the key difference.

Because sino is introducing a contrast or correction, and in writing Spanish it is normally separated with a comma in this kind of structure.

So the standard written form is:

• No quiero la pequeña, sino la grande.

In speech, you naturally pause before sino, and the comma reflects that pause.

Yes. You can repeat the noun, especially if you want to be extra clear.

For example:

• No quiero la camiseta pequeña, sino la camiseta grande.
• No quiero la camiseta pequeña, sino la grande.

The second version is often more natural because Spanish usually avoids repeating a noun when the meaning is already obvious.

Quiero is the yo form of querer in the present indicative.

• querer = to want
• yo quiero = I want

So:

• No quiero... = I don’t want...

This is the normal way to express a present choice or preference.

Gran is a shortened form of grande used only before a singular noun.

• una gran casa = a great/big house

But when the adjective stands on its own, as it does here after la, you use grande, not gran:

• la grande = the big one

So la gran would not work here.

Also, remember that gran often has the sense of great or important, not just physically big.

Yes. If la pequeña and la grande referred to people, you would usually need the personal a.

For example:

• No quiero a la pequeña, sino a la grande.

That is because Spanish normally uses a before a specific human direct object.

If you are talking about objects, you do not use that a:

• No quiero la pequeña, sino la grande.

Yes. Their exact meaning depends on context.

They can refer to:

• physical size: the small one / the big one
• age: the younger one / the older one
• rank or version: the smaller model / the larger model

So the grammar stays the same, but the real meaning comes from the situation.

Yes, it is completely natural. It is a normal way to choose between two feminine things when the noun is already understood.

For example, in a shop:

• No quiero la pequeña, sino la grande.

A speaker from Spain would understand this immediately if the object being discussed is clear.

Yes, often you could.

• No quiero la pequeña, sino la grande.
  This clearly contrasts two options.

• Prefiero la grande.
  This simply says I prefer the big one.

Both are natural, but the first one more explicitly rejects one option and replaces it with the other.

Yes, because it shows which option is rejected and which one is chosen.

• No quiero la pequeña, sino la grande.
  → not the small one; the big one instead

If you reverse them:

• No quiero la grande, sino la pequeña.
  → not the big one; the small one instead

So the structure is fixed in meaning:

• first = the option rejected
• second = the option chosen instead