No quiero el pequeño; prefiero el grande.

Because in this sentence they are being used like nouns: el pequeño = the small one and el grande = the big one.

Spanish often uses definite article + adjective to avoid repeating a noun that is already understood from context. For example, if you are choosing between two shirts, el pequeño means the small one.

Spanish very naturally leaves out a noun when it is obvious from context. Instead of repeating something like el vaso pequeño and el vaso grande, a speaker can simply say el pequeño and el grande.

English does this too with the small one and the big one, but Spanish uses the article plus the adjective directly.

If you say Quiero pequeño, that sounds incomplete in standard Spanish because pequeño is an adjective and normally needs a noun to describe.

Adding el turns it into a noun phrase: el pequeño = the small one.

So:

• Quiero el pequeño = I want the small one
• Quiero un coche pequeño = I want a small car

Gran is a special shortened form of grande used only before a singular noun, and it usually means great or sometimes big depending on context.

Examples:

• un gran libro = a great book
• una gran casa = a big house or a great house

But here the adjective stands on its own after the article, so Spanish uses the full form:

• el grande
• not el gran

Spanish often leaves out subject pronouns because the verb ending already shows who is doing the action.

• quiero = I want
• prefiero = I prefer

So yo is not necessary unless you want emphasis or contrast:

• Yo prefiero el grande, no tú.

In normal conversation, omitting yo is more natural.

Because preferir is a stem-changing verb in the present tense. The e in the stem changes to ie in most forms.

Examples:

• yo prefiero
• tú prefieres
• él/ella prefiere
• nosotros preferimos
• vosotros preferís
• ellos prefieren

So prefiero is the correct I form of preferir.

In Spanish, basic negation is usually formed by putting no directly before the verb.

So:

• Quiero el grande = I want the big one
• No quiero el pequeño = I don’t want the small one

This is one of the most common sentence patterns in Spanish.

They agree with an implied masculine singular noun.

For example, if the hidden noun were libro or vaso, you would use:

• el pequeño
• el grande

If the implied noun were feminine, you would change the article and adjective:

• la pequeña
• la grande

So the form depends on the noun being understood from context.

Yes. If the omitted noun were feminine, the sentence would be:

No quiero la pequeña; prefiero la grande.

For example, if you were talking about two boxes and the noun was feminine, Spanish would use feminine agreement.

Because el grande is the object of prefiero. The basic structure is:

prefiero + noun phrase

Here, the noun phrase is el grande.

So:

• Prefiero el grande means
• I prefer the big one

This is normal Spanish word order.

The semicolon links two closely related statements:

• No quiero el pequeño
• prefiero el grande

It shows a stronger break than a comma, but the ideas are still closely connected. A full stop would also be possible:

No quiero el pequeño. Prefiero el grande.

In everyday writing, many people would use a full stop. The semicolon is correct and slightly more formal or stylistic.

No, but it is a very common and neutral choice. Depending on context, Spanish might also use words like chico or pequeñito, but those can differ in tone, region, or nuance.

In standard Spanish from Spain, pequeño is a safe, normal word for small. In this sentence, it sounds natural.

Yes, but that means something slightly different.

• el pequeño / el grande = the small one / the big one
• el más pequeño / el más grande = the smallest one / the biggest one

So adding más turns it into a superlative comparison within a group, not just a contrast between two options.