Haec coniugatio facilis est, illa autem difficilior; tamen utraque coniugatio discipulis discenda est.

Because coniugatio is a feminine singular noun.

Both haec (this) and illa (that) are demonstrative adjectives/pronouns agreeing with coniugatio in gender, number, and case:

• haec coniugatio = this conjugation
• illa coniugatio = that conjugation

If the noun were masculine, you would expect forms like hic or ille instead.

They are both in the nominative singular.

You can tell because each is the subject of its clause:

• Haec coniugatio facilis est = This conjugation is easy
• illa autem difficilior = that one, however, is more difficult

Even in the second clause, est is understood from the first clause, so illa coniugatio is still functioning as the subject.

Because the sentence is making a comparison.

• facilis = easy (positive degree)
• difficilior = more difficult (comparative degree)

Latin often uses the comparative when two things are being directly compared. Here the idea is:

• this conjugation is easy
• that one is more difficult

A learner might expect difficilis, but difficilior makes the contrast stronger by explicitly comparing the two.

Also, difficilior is nominative singular and agrees with coniugatio. In the comparative, the same form is used for masculine and feminine nominative singular.

Because Latin often leaves out words that are easily understood from context.

So:

• Haec coniugatio facilis est, illa autem difficilior

really means:

• Haec coniugatio facilis est, illa autem difficilior est

The second est is omitted because it is obvious. This is very common in Latin.

Because autem is a postpositive word.

That means it usually comes second in its clause, not first. So Latin prefers:

• illa autem difficilior

rather than:

• autem illa difficilior

Here autem means something like however, but, or on the other hand.

This placement is normal and something Latin learners see often with words like autem, enim, and vero.

They have different jobs:

• autem = however / but / on the other hand
• tamen = nevertheless / still / even so

So the sentence first gives a contrast:

• this conjugation is easy, that one however is more difficult

Then it adds a surprising or important follow-up:

• nevertheless, both/each of the two conjugations must be learned

So autem contrasts the two conjugations, while tamen introduces the idea that, despite the difference in difficulty, the learner still has to learn both.

Utraque means each of the two or, more naturally in English here, both.

It comes from uterque, utraque, utrumque, which is used when talking about two things. That is important: it is specifically a word for two, not for a larger group.

So:

• utraque coniugatio literally = each conjugation of the two
• more naturally = both conjugations

Because uterque / utraque / utrumque is grammatically singular, even though it refers to two items taken one by one.

So Latin says:

• utraque coniugatio

literally something like:

• each conjugation

But in English we often translate it more naturally as:

• both conjugations

This is a very common point of confusion. Latin is thinking distributively: each one of the two.

That is also why the verb phrase is singular:

• discenda est = must be learned not
• discendae sunt

because the grammatical subject is singular: utraque coniugatio.

Because with the gerundive of obligation (also called the passive periphrastic), Latin often uses the dative of agent.

So:

• discipulis discenda est

means literally:

• it is to-be-learned for the students

More natural English:

• the students must learn it
• it must be learned by the students

Here discipulis is not a direct object. It is the people on whom the obligation rests.

This construction is very common:

• Carthago delenda est Romanis = Carthage must be destroyed by the Romans / the Romans must destroy Carthage

It is a gerundive + est construction, often called the passive periphrastic.

Break it down:

• discenda = gerundive of disco, discere (to learn)
• est = is

So literally:

• discenda est = is to be learned

In context, this usually expresses necessity or obligation:

• must be learned

Because coniugatio is feminine singular nominative, the gerundive is also feminine singular nominative:

• coniugatio ... discenda est

If the noun were plural, the gerundive and verb would change accordingly.

That is exactly how the gerundive works here.

Even though disco means learn, the gerundive gives the sense to be learned. So the subject is not the person doing the action, but the thing that needs the action done to it:

• coniugatio discenda est = the conjugation must be learned

Latin then adds the person responsible in the dative:

• coniugatio discipulis discenda est = the conjugation must be learned by the students / the students must learn the conjugation

So the grammar is passive in form, but the meaning often corresponds to an English active sentence with must.

Since coniugatio is feminine singular nominative, the words describing or referring to it match that form:

• haec coniugatio
• illa coniugatio
• utraque coniugatio
• facilis agrees with coniugatio
• difficilior agrees with coniugatio
• discenda agrees with coniugatio

This is a good sentence for seeing Latin agreement in action: demonstratives, adjectives, and gerundives all match the noun they go with.

Yes: it is built in a very balanced way.

First, it contrasts two items:

• Haec coniugatio facilis est
• illa autem difficilior

Then it gives a conclusion applying to both:

• tamen utraque coniugatio discipulis discenda est

So the logic is:

1. one conjugation is easier
2. the other is harder
3. nevertheless, both have to be learned

That makes the sentence a useful example of how Latin organizes contrast and conclusion with words like autem and tamen.