You can use either, it just depends what context you are in.
For example, either of the versions of these sentences are fine:
Since both words mean the same thing, it doesn't utterly matter.
Take a look at these two versions:
You might feel in certain instances that one or the other word is preferable, but in the examples above, it does not really show much of a noticeable difference.
As i got nearer to the kitchen, the smell of the pizza sauce smelled even better
No, "closer" is not a preposition; it is an adjective. Prepositions typically show the relationship between a noun/pronoun and other words in a sentence.
"Nearer" is an adjective.
Nearer is not a verb and does not have any tenses. Near is a verb, and the past tense is neared.
use ize in sentence
nearer
That storm's getting closer.
It is nearer to England.
Um... closer to what...? depends were you live
Ireland is closer to the North Pole, as it is about 53°N.
A sentence closer is at the end of the sentence and normally, before the closer, there's a comma.-.-
Example sentence - The painting appeared dimensional until you looked closer.
Among the two Venus is closer to the Sun
It is nearer to one half.
He moved to be closer to the warmth of the fire.
As i got nearer to the kitchen, the smell of the pizza sauce smelled even better
4/7 is closer to 1.