Comparamos el portafiltro con el filtro de café.

Comparamos is the 1st person plural form of comparar.

It can mean either:

• we compare — present tense
• we compared — preterite / simple past

For -ar verbs, those two forms happen to look the same in nosotros.

So the exact tense depends on context. In a sentence like this, especially in an explanation, demonstration, or instruction, it will often be understood as present: we compare.

Spanish often drops subject pronouns when the verb ending already makes the subject clear.

• Comparamos already tells you the subject is we
• so nosotros is not necessary

You could say:

• Nosotros comparamos el portafiltro con el filtro de café

but it sounds more marked, as if you want to emphasize we specifically.

This omission of subject pronouns is very common in Spanish.

Because both nouns are being treated as specific items or as the named objects under discussion.

Spanish uses the definite article much more often than English does. So where English might sometimes say something like compare portafilter with coffee filter in a label or instruction, Spanish normally prefers:

• el portafiltro
• el filtro de café

In a normal full sentence, keeping el sounds natural.

Because comparar X con Y is the normal way to say to compare X with Y.

So:

• Comparamos el portafiltro con el filtro de café = we compare the portafilter with the coffee filter

You may also see comparar X a Y, but that is usually more like to liken X to Y, and it often sounds more literary or stylistic.

For everyday comparison, con is the safest choice.

Because Spanish usually does not use one noun directly as an adjective the way English often does.

English can stack nouns:

• coffee filter
• car door
• kitchen table

Spanish usually uses a structure with de:

• filtro de café
• puerta del coche
• mesa de cocina

So de café means something like for coffee / related to coffee / coffee-type.

Because de café describes the type or purpose of the filter, not a specific coffee.

• filtro de café = coffee filter
• filtro del café = the filter of the coffee

The second version would usually refer to a specific coffee already mentioned, which is not the idea here.

So when naming the object in general, filtro de café is the natural choice.

Yes. Portafiltro is a compound noun, and it is written as one word.

It is commonly used for the part that holds the filter, especially in coffee-making contexts.

It is also masculine, which is why the sentence uses:

• el portafiltro

Its plural is:

• los portafiltros

You usually just have to learn the gender of the noun as part of the word.

In this case, the standard form is:

• el portafiltro

Many compound nouns in Spanish have fixed grammatical gender that must be memorized. Even though endings can sometimes help, they are not always enough, especially with compound words like this one.

So the important thing to remember is simply:

• el portafiltro
• los portafiltros

Yes, you might hear filtro para café, but filtro de café is the more usual way to name the object itself.

Very roughly:

• filtro de café = a coffee filter
• filtro para café = a filter for coffee

Both can be understandable, but de café sounds more like the normal name of the item.

Because the personal a is mainly used with people and sometimes pets or very personified beings, not ordinary objects.

Here, el portafiltro is a thing, so we say:

• Comparamos el portafiltro...

not:

• Comparamos al portafiltro...

So this sentence has a normal direct object with no personal a.

Yes, it is completely normal.

Spanish word order is more flexible than English word order. Starting with the verb is very common, especially when the subject is omitted:

• Comparamos el portafiltro con el filtro de café

If you want, you can also make the subject explicit:

• Nosotros comparamos el portafiltro con el filtro de café

Both are grammatical, but the version without nosotros is more natural in most contexts.