Learn Hardcore Esperanto: Mi amas nian hejmon pli ol la domon de la najbaro. - I love our home more than the neighbor's house.

Accusative -n on the noun
Hejmon has -n because it is the direct object of amas (to love).
- Mi amas nian hejmon. = I love our home.
  Direct objects in Esperanto normally take -n.
Agreement of the adjective/pronoun
Nian is a possessive adjective (from ni = we). Adjectives must agree in number and case with the noun they describe. Since hejmon is in the accusative singular, nian must also be accusative singular:
- nominative: nia hejmo
- accusative: nian hejmon

So nian hejmon is just the correctly inflected form of nia hejmo when it’s the direct object.

Why does hejmon have -n, but najbaro in de la najbaro does not?

Hejmon has -n because it is the direct object of the verb amas.
Najbaro stands after the preposition de (of, from).

In Esperanto, a noun after a preposition is normally not in the accusative:

la domo de la najbaro = the house of the neighbour

So:

nian hejmon → object of amas → accusative -n
la najbaro → object of de → no accusative -n

Why is there no la before nian hejmon, but there is la before domon?

In Esperanto, you don’t need the definite article la in front of possessive adjectives like mia, nia, via, etc.:

nia hejmo = our home (normally understood as definite already)
la nia hejmo is unusual and usually unnecessary.

But domon de la najbaro is not directly possessed by a possessive adjective. To say the neighbour’s house, Esperanto commonly uses:

la domo de la najbaro

Here la marks a specific house and la najbaro a specific neighbour.

So:

nian hejmon → possessive adjective already makes it clearly “our (specific) home”
la domon de la najbaro → needs la to mark which house and which neighbour

What is the difference between hejmo and domo?

hejmo = home (emotional, personal, “where you belong”)
domo = house (physical building)

So in the sentence:

nian hejmon = our home (the place we live and feel attached to)
la domon de la najbaro = the neighbour’s house (just the building)

This mirrors English: home vs house.

Why is it pli ol la domon and not pli ol la domo?

This touches a well-known detail of Esperanto grammar.

The structure is:

Mi amas nian hejmon pli ol la domon de la najbaro.

Here, both nian hejmon and la domon de la najbaro function as direct objects of amas in the comparison:

I love X more than (I love) Y.

Because both are objects, many writers keep them in the same case (accusative):

nian hejmon … la domon

However, grammatically:

If ol is treated as a conjunction (like than), then the hidden part is:
- Mi amas nian hejmon pli ol (mi amas) la domon de la najbaro.
- The second object domon correctly takes -n.
If ol is treated as a preposition, then domo would stay in nominative: ol la domo.

Both patterns are used in practice. The version you have keeps the accusative in both parts, which is very common and clear:

nian hejmon (object)
la domon (object)

Could the sentence mean “I love our home more than I love the neighbour”?

No, not in the form given.

Your sentence is:

Mi amas nian hejmon pli ol la domon de la najbaro.

The part after ol is clearly la domon de la najbaro (the neighbour’s house), not la najbaron (the neighbour).

If you wanted to say “I love our home more than I love the neighbour,” you’d say:

Mi amas nian hejmon pli ol la najbaron.

So the original sentence is unambiguously about two houses/home-like things, not about a person.

Why is it de la najbaro and not something like najbara domo?

Both are possible, but they have slightly different flavours:

la domo de la najbaro
- Literally the house of the neighbour
- Very neutral and common way to express possession.
la najbara domo
- Literally the neighbouring house / the neighbour’s house
- Focuses more on the house as a neighbouring house (adjectival idea).
- Could sometimes be understood as the house that is nearby rather than the house owned by the neighbour.

De la najbaro makes the owner explicit. Najbara domo stresses more the adjacent/neighboring character of the house, though in context it can also mean the neighbour’s house.

Can the word order be changed, for example: Mi amas pli nian hejmon ol la domon de la najbaro?

Yes, some variation is possible, but not all orders sound equally natural.

Most natural:

Mi amas nian hejmon pli ol la domon de la najbaro.

Also acceptable, with extra emphasis on the degree:

Mi pli amas nian hejmon ol la domon de la najbaro.

Less natural or potentially confusing:

Mi amas pli nian hejmon ol la domon de la najbaro.
Sounds odd; pli usually directly precedes the word or phrase being compared, or the verb.

Avoid:

Mi amas nian hejmon ol la domon de la najbaro pli.
The pli at the end is confusing and unidiomatic.

So it’s best to keep:

pli just before the verb (pli amas) or
in the standard comparative pattern (X pli ol Y).

Could I say Mi amas nian hejmon pli multe ol la domon de la najbaro?

Yes, you can.

pli multe = more (in quantity/degree)

Mi amas nian hejmon pli multe ol la domon de la najbaro is grammatically correct and clear.
However, in many contexts pli ol after a verb of feeling like amas already implies “more (in degree)”, so simply:

Mi amas nian hejmon pli ol la domon de la najbaro is usually enough and more natural.

What would the sentence look like in the plural, e.g. “We love our homes more than the neighbours’ houses”?

You would pluralize the nouns and make all adjectives agree:

Ni amas niajn hejmojn pli ol la domojn de la najbaroj.

Breakdown:

Ni = we
amas = love
niajn hejmojn = our homes
- nia → niajn (plural + accusative)
- hejmo → hejmojn (plural + accusative)
la domojn = the houses (accusative plural)
de la najbaroj = of the neighbours (plural nominative after de)