Frater studiosior est quam soror, sed soror diligentius versus repetit.

The sentence has two clauses joined by sed (but).

In Frater studiosior est quam soror:

• frater = subject
• est = verb
• studiosior = predicate adjective describing frater
• quam soror = comparison phrase, than sister

In sed soror diligentius versus repetit:

• soror = subject
• repetit = verb
• versus = direct object
• diligentius = adverb modifying repetit

So the first clause says what the brother is like, and the second says how the sister does an action.

Studiosior is the comparative form of studiosus.

• studiosus = studious, eager
• studiosior = more studious, more eager

Latin often forms the comparative adjective by adding -ior for masculine/feminine nominative singular.

Here it agrees with frater, which is masculine singular, so studiosior means more studious and describes the brother.

After quam in a straightforward comparison, Latin usually puts the second thing being compared in the same case as the first.

Here:

• frater is nominative
• so soror is also nominative after quam

That is why Latin says quam soror, not quam sororem.

English does something similar in careful grammar when we say he is taller than she is, though everyday English often uses than her.

Yes. That is another normal Latin way to express the same comparison.

Latin has two common patterns:

• studiosior quam soror
• studiosior sorore

The second uses the ablative of comparison, so sorore would be ablative singular.

So both of these can mean:

• The brother is more studious than the sister.

Because diligentius is an adverb, while diligentior is an adjective.

In the second clause, the word describes how the sister repeats the verses. It modifies the verb repetit, not the noun soror.

• diligentior = more careful / more diligent, describing a person or thing
• diligentius = more carefully / more diligently, describing an action

So Latin uses diligentius because the meaning is she repeats more carefully, not she is more careful.

It is the comparative adverb from diligens or from the adverb diligenter.

A simple way to remember it is:

• adjective: diligens = careful, diligent
• adverb: diligenter = carefully
• comparative adverb: diligentius = more carefully

This matches a very common Latin pattern:

• comparative adjective: -ior
• comparative adverb: -ius

So:

• studiosior = more studious
• diligentius = more carefully

Here versus is a noun meaning verses or lines of poetry.

It is the direct object of repetit, so it is in the accusative.

This form can be tricky because versus belongs to the fourth declension, where some forms look the same. In this sentence, it is understood as accusative plural: verses.

So versus repetit means repeats the verses or goes over the verses again.

Latin could sometimes leave the subject out, because the verb ending already shows the person and number. So sed diligentius versus repetit would still be understandable.

But repeating soror is very natural here because it creates a clear contrast:

• Frater ...
• sed soror ...

So the repetition helps emphasize the comparison between the brother and the sister.

Because classical Latin does not have articles like English the and a/an.

So:

• frater can mean brother, a brother, or the brother
• soror can mean sister, a sister, or the sister

You understand which is meant from the context, not from a separate article.

Latin word order is much more flexible than English word order because the endings show the grammatical roles.

This sentence could be rearranged in several ways and still mean basically the same thing. For example, Latin could move studiosior, diligentius, or versus for emphasis.

The given order is natural and clear:

• Frater studiosior est quam soror sets up the first comparison
• sed soror diligentius versus repetit gives the contrasting second point

So the word order is not random, but it is also not as fixed as English word order.

They do not describe exactly the same kind of thing.

• studiosior describes a quality of the person: the brother is more studious, more eager, more devoted to study
• diligentius describes the manner of an action: the sister repeats the verses more carefully

So the sentence contrasts two different ideas:

• the brother may be more studious
• but the sister works more carefully at this task

That contrast is one of the main points of the sentence.