"This is not an apple."

Translation: Ez nem egy alma.

[Curashu]

Can it be like "ez sem alma"?

[BenceFerdinandy]

That would mean "This is also not an apple." See a reference here: http://www.hungarianreference.com/Misc_Grammar/negatives-nem-ne-sem-se.aspx

[IreneSinQueso]

What's exactly the difference between "ez" and "az/a"? I understand az/a refers to an object but not one specifically... Is that right?

[BenceFerdinandy]

Az has two functions, so I guess is slightly confusing.
this = ez;
that = az;
this apple = ez az alma;
these apples = ezek az almák;
that apple = az az alma;
that chair = az a szék; those chairs = azok a székek

(Note that the definite article az/a is needed in Hungarian but not in English)

[tijana.puh]

And why can't I say ez alma nem?

[Pgloc]

Well for one, the indefinite article (egy) is missing. Furthermore the word order is important, if you change it, then it will sound unnatural or have a different meaning.

[Sunny30356]

Whats different between ez and az

[jzsuzsi]

Here, ez is this, az is that.