We include 'de' when an adjective precedes a verb and when a noun precedes a verb.
These two sentences:
Ca prend trop de temp (It takes too much time)
Ca fait un grand difference (It makes a big difference)
Why aren't we including 'de' between grand and difference?
Ca fait une grande différence: it is specific, there is just 1 difference, no more, you basically have to pick between 'de' and 'un(e)', you can't use both at once like you are suggesting.
As Aline has said already, your issue is one of quantity. "A big difference" is understood as one "thing" whereas "too much time" is subject to interpretation or context.
If in English your sentence defines a definite quantity or character, the "de" is generally not needed.
Now...think of this example: Il n'y a pas trop de difference.
What is difference between this and your example? The difference is that in your example, you are declaring that there is indeed a big difference. In the above example, it is being declared that there is a difference, but there is no indication by count or quality what that difference is.
Your example is not really a very good one to illustrate your point.
I'll try and find a better one when I have a bit more time later.
Not a lot of sense, but some. Hah! Another example.
It's remarkable similar to English, in fact.
[1] Now, if someone can try and clarify when and why some adjectives precede, some follow, the noun, I'd like to see it. I've tried, and failed, to formulate rules to explain it. There are clearly some classes of modifier that take one way or the other, but in that example, why is it 'une voiture neuve' or 'une nouvelle voiture'? I know that either is correct, but that 'une neuve voiture' or 'une voiture nouveau' is not, and I'm happy enough that I won't make that sort of mistake, but I've never really been able to state exactly why.
http://www.bertrandboutin.ca/Folder_..._place_adj.htm
Or for a summarized list:
I was taught modifiers that describe "beauty, age, goodness, size" ("BAGS-words") go before, otherwise they go after.
une voiture neuve describes the state of the car, hence it goes before. there may also be a difference between collective nouns, but i believe the BAGS rule takes precedence.
btw, it's le verre ;-)
I could see that, potentially, a nouvelle voiture could refer to the fact that I'm getting a new (to me) car, but not a new (from the factory) one, but it's stil an age-related modifier. Similar with ancien/vieux/agé. I know which way round to put them, but not why, and the rule you mention, while useful, is not consistent, as far as I can tell.
Well I never.
Some examples:
Un nouvel hôpital va bientôt voir le jour
Un nouveau bâtiment va être érigé d'ici la fin de l'année
Je me suis installée en Suisse où j'ai commencé une nouvelle vie
J'ai appris un mot nouveau chaque jour pendant mon séjour à l'étranger
Murdpch est un homme vieux et cruel
Un vieil homme habite dans notre immeuble
Edith est une vieille femme de huitante sept ans
Une vieille femme nourissait les chats érrants du quartier
Une femme âgée habite seule dans cet immeuble
1. assez, peu, beaucoup, trop, plus, moins - and their negation (pas assez, pas beaucoup, pas trop, etc.) are adverbs of quantity followed by " de/d'" before the noun they quantify in the following eg:
Paul a assez d' argent / n'a pas assez d'argent (has enough money, ....)
Il y a peu de sauce dans la salade
Nous avons beaucoup de livres à la bibiothièque /pas beaucoup de livres...
Il y a trop de mayonnaise dans la sauce.
2. In the sentence "une grande différence ", grande is an adjective that specifies "différence" and as such, in general precedes or follow immediately the noun without any conjonction like "de", eg:
Une grande bouteille , une jolie fille , un vieil homme, un forum intéressant, la grande porte , le petit chalet , etc...
This for the 2 first questions...hope its not more confusing...
Hope it helps!