Prefiro a roda de oleiro, ao passo que Ana prefere moldes.

Because the verb preferir is being conjugated for two different subjects:

• eu prefiro = I prefer
• ela prefere = she prefers

So in this sentence:

• Prefiro... → the subject is understood as I
• Ana prefere... → the subject is Ana

This is very common in Portuguese, because the subject pronoun is often left out when the verb ending already makes it clear.

Portuguese often omits subject pronouns when they are not needed.

So instead of saying:

• Eu prefiro a roda de oleiro...

it is perfectly natural to say:

• Prefiro a roda de oleiro...

The ending -o in prefiro already shows that the subject is I.

This is much more common in Portuguese than in English.

Roda de oleiro literally means potter’s wheel.

Breakdown:

• roda = wheel
• oleiro = potter
• de oleiro = of a potter / potter’s

So the phrase is not just any wheel, but the specific wheel used by a potter.

Because roda is a feminine singular noun, and here it is being used with the definite article:

• a roda de oleiro = the potter’s wheel

Even when English might use no article in a general statement, Portuguese often uses one.

Here, preferir takes a direct object, and that object can naturally appear with the article:

• Prefiro a roda de oleiro = I prefer the potter’s wheel / I prefer using the potter’s wheel

So the article is normal and idiomatic.

Because moldes is being used in a general sense: moulds / molds in general, not a specific set already identified.

So:

• Ana prefere moldes = Ana prefers moulds

If the speaker meant specific moulds, Portuguese could use the article:

• Ana prefere os moldes = Ana prefers the moulds / those moulds

This contrast between bare plural and article + plural is very common in Portuguese.

Ao passo que is a connector meaning something like:

• whereas
• while
• by contrast
• whereas, on the other hand

It introduces a contrast between two statements.

So here it contrasts the two preferences:

• Prefiro a roda de oleiro, ao passo que Ana prefere moldes.

This is a bit more formal or polished than just using mas.

Compare:

• ..., mas Ana prefere moldes. = ...but Ana prefers moulds.
• ..., ao passo que Ana prefere moldes. = ...whereas Ana prefers moulds.

The second sounds more explicitly contrastive and slightly more formal.

Yes, generally yes. It is not wrong in everyday language, but it tends to sound more written, careful, or formal than simpler alternatives like:

• mas = but
• enquanto = while / whereas

So a learner should understand it well, but in casual speech people may more often choose a simpler connector.

Because ao passo que introduces a second clause that contrasts with the first one.

The comma helps separate the two ideas:

• Prefiro a roda de oleiro, ao passo que Ana prefere moldes.

This punctuation is standard and natural in written Portuguese.

In standard written Portuguese, proper names often appear without an article:

• Ana prefere moldes.

However, in European Portuguese, using an article with personal names is very common, especially in speech:

• a Ana prefere moldes

So both can occur, but:

• Ana without the article is very normal in writing
• a Ana is very common in everyday European Portuguese, especially spoken language

Moldes is the plural of molde.

• molde = mould / mold
• moldes = moulds / molds

It is a masculine noun:

• o molde
• os moldes

In the sentence, the article is omitted because the meaning is general.

Yes. Very naturally.

Even though a roda de oleiro has the article a, the sentence can still express a general preference for one method or tool over another:

• I prefer the potter’s wheel, whereas Ana prefers moulds.

So this is not necessarily about one single wheel and one particular set of moulds. It can simply contrast two ways of working.

Yes, in many contexts it could.

For example:

• Prefiro a roda de oleiro, enquanto a Ana prefere moldes.

Here enquanto can mean whereas / while, not just during the time that.

But ao passo que makes the contrast especially clear and often sounds more formal or more written.

Yes. Portuguese often uses de + noun where English uses a possessive structure or an adjective-like noun.

So:

• roda de oleiro = potter’s wheel
• literally: wheel of potter

This is a very common pattern in Portuguese.