"Nudeln" is a slightly more general term. We normally use 'Pasta' only to refer to Italian kinds of noodles. If you are sitting in an Italian restaurant, they are equivalent. But you wouldn't normally refer to spaetzle as 'Pasta'. But you asked whether you can get away with 'Pasta'. Yes, you can. Nobody will tar and feather you for using it. It's not actually wrong and you will be understood.

It's exactly like English. All pasta is noodles but not all noodles are pasta

You were confused in some things: A) There's no continuous aspect in german, that is: - "I eat" = "Ich esse", or - "I am eating" = "Ich esse", but - "I am eating" can not be said like "Ich bin essen". That does not exist in german. (You always use the present tense itself to mean both "i eat" or "i am eating".)

Since there isn't this continuos aspect, your try should be "Der Mann isst nicht Nudeln" (because you're not trying infinitive "essen" anymore), but this is also wrong, because of the negation. For this, I found this helpful page:

http://www.nthuleen.com/teach/grammar/negationexpl.html Which I also copied and pasted below (that's not mine):

Handout: Negation with Nicht and Kein

Use kein (and its inflected forms keine/keinen):

• to negate a noun preceded by ein/eine/einen: - Ist das eine Lampe? - Nein, das ist keine Lampe.

• to negate a noun preceded by no article at all (although it may be preceded by an adjective): - Finde ich Bücher hier? - Nein, Sie finden keine Bücher hier. - Finde ich gute Bücher hier? - Nein, Sie finden keine guten Bücher hier.

Use nicht:

• to negate a noun preceded by a definite article (der/die/das) or a possessive pronoun (mein/dein/etc): - Ist das dein Buch? - Nein, das ist nicht mein Buch. - Ist er der Lehrer? - Nein, er ist nicht der Lehrer. (Er ist kein Lehrer would mean that he’s not a teacher at all.)

• to negate entire thoughts, verbs, adjectives, and elements of the sentence other than nouns: - Verstehst du? - Nein, ich verstehe nicht. - Spielst du gern Tennis? - Nein, ich spiele nicht gern Tennis. - Ist die Uhr alt? - Nein, sie ist nicht alt.

Hope that helps!

This^

I did it too, and ofcourse it failed. Can someone please explain why ?

I agree with christian that you can't bring English grammar into this. Maybe it sounds better to you because you are trying to replace "not" with "nicht" as English doesn't have something similar to "kein". The meaning of German sentences is more based on context which can be complicated if you only have one sentence. If I read a sentence like "Nudeln isst der Mann nicht" I would actually think the opposite of what you are saying as to me it could mean that he never eats pasta.

English grammar doesn't apply to German.

Not sure about that. "Der Mann isst keine Pasta" sounds more natural to me.

I agree with you. I think "Der Mann isst keine Nudeln" sounds more like "The man does not eat pasta" (like it's his habit not to eat pasta) rather than "The man is not eating pasta" (like just at this moment he is not eating pasta). It may be more idiomatic to use "keine," but it depends on the context. The contexts I can think of in which one would say "The man is not eating pasta" (i.e. "The man is not eating pasta, but rather rice") it would be make more sense to say "Der Mann isst nicht Pasta."

I don't think christian meant that English and German are totally incomparable. I think he meant that you have to be careful with taking concepts from one language's grammar to explain another.

@penelope: christian and myself are both native speakers of German and we agree that 'Isst keine Pasta' is clearly preferable here. Christian's observation that you can't use closeness to English grammar as an argument for or against constructions in German is a valid point.