Die nieuwe scooter schijnt minder lawaai te maken dan de oude.

Here die is a demonstrative pronoun/determiner, meaning something like that or that particular.

• de nieuwe scooter = the new scooter
• die nieuwe scooter = that new scooter

So die adds a pointing/emphasizing sense. It suggests the speaker is talking about a specific scooter already known in the conversation.

In this sentence, schijnt comes from schijnen and means seems or appears.

So:

• Die nieuwe scooter schijnt... = That new scooter seems...

Be careful: schijnen can also mean to shine in other contexts.

Examples:

• De zon schijnt. = The sun is shining.
• Hij schijnt ziek te zijn. = He seems to be ill.

Here it clearly has the seems/appears meaning.

After schijnen meaning to seem, Dutch often uses te + infinitive.

So the pattern is:

• schijnen + te + infinitive

Examples:

• Hij schijnt moe te zijn. = He seems to be tired.
• Ze schijnt hard te werken. = She seems to work hard / She seems to be working hard.
• Die scooter schijnt minder lawaai te maken. = That scooter seems to make less noise.

This is a very common structure and is something English speakers simply need to get used to.

Because Dutch often places the main infinitive at the end when another verb is already conjugated earlier in the clause.

In this sentence:

• schijnt is the conjugated verb
• maken is the infinitive that belongs at the end

The structure is:

• subject + finite verb + other elements + te + infinitive

So:

• Die nieuwe scooter = subject
• schijnt = finite verb
• minder lawaai = object/phrase
• te maken = infinitive phrase at the end

This kind of word order is very typical in Dutch.

Lawaai maken is a fixed expression meaning to make noise.

• lawaai = noise
• maken = make/do

Together:

• lawaai maken = to make noise

Dutch often uses maken in expressions where English uses make too, so this one is fairly straightforward.

Example:

• De kinderen maken veel lawaai. = The children are making a lot of noise.

Minder lawaai means less noise. Here Dutch is comparing the amount of noise, not directly describing the scooter with an adjective.

So:

• minder lawaai maken = to make less noise

You could also describe something as:

• lawaaierig = noisy

But that would create a different structure, for example:

• Die nieuwe scooter is minder lawaaierig dan de oude. = That new scooter is less noisy than the old one.

Both are possible, but your sentence uses the common expression less noise / less noisy-sounding in terms of amount of noise produced.

In standard Dutch:

• dan is used after a comparative
• als is used in equality comparisons

So:

• groter dan = bigger than
• minder ... dan = less ... than
• even groot als = as big as

In your sentence:

• minder lawaai ... dan de oude = less noise ... than the old one

That is why dan is correct here.

De oude means the old one.

Dutch often leaves out the noun when it is already obvious from context. So:

• de oude scooter = the old scooter
• de oude = the old one

The noun scooter is understood, so repeating it is unnecessary.

Full version:

• Die nieuwe scooter schijnt minder lawaai te maken dan de oude scooter.

Natural shorter version:

• ... dan de oude.

Because scooter is a de-word:

• de scooter
• therefore: de oude scooter
• and when the noun is omitted: de oude

If the missing noun were a het-word, then you would get het oude instead.

Example:

• het huis = the house
• het oude = the old one

So the article stays consistent with the noun being understood.

It sounds somewhat uncertain or indirect.

Schijnt suggests:

• it seems
• apparently
• it appears that

So the speaker is not presenting it as a hard fact in the strongest possible way.

Compare:

• Die nieuwe scooter maakt minder lawaai dan de oude. = That new scooter makes less noise than the old one.
  More direct/factual.

• Die nieuwe scooter schijnt minder lawaai te maken dan de oude. = That new scooter seems to make less noise than the old one.
  More cautious/indirect.

Yes, often you can.

• Die nieuwe scooter lijkt minder lawaai te maken dan de oude.

This also means The new scooter seems to make less noise than the old one.

However, there can be a slight nuance:

• lijkt often sounds like it appears/seems based on impression
• schijnt can sometimes suggest it is said/apparently or it seems

In many everyday contexts, though, both are possible.

The sentence follows the usual Dutch main clause pattern where the conjugated verb is in second position.

Breakdown:

• Die nieuwe scooter = subject
• schijnt = finite verb
• minder lawaai = object/phrase
• te maken = infinitive phrase
• dan de oude = comparison phrase

So the pattern is roughly:

• Subject + finite verb + rest + infinitive + comparison

That is a very normal Dutch structure.

You could say:

• De nieuwe scooter schijnt minder lawaai te maken dan de oude.

This means essentially the same thing, but it sounds a bit more neutral:

• die nieuwe scooter = that new scooter
• de nieuwe scooter = the new scooter

So die adds a bit of pointing/emphasis, while de is more plain and neutral.