"Til" and "For"

Both mean “for,” but sometimes, when I confuse one for the other, a mistake always shows up, so can anyone please enlighten me for the following:-
" Nå ringer det på døra, og Ben går for å åpne for gjestene" meaning “Now someone rings at the door, and Ben goes to open (it) for the guests”
" Ja, her er presangene til barna" meaning “Yes, here are the presents (cf. gavene) for the children.”

So when do I use which for the word “for”, please?

This is a really difficult question. I’m not Norwegian, I’m a learner like you, so I can only state my impression of the difference over usage I’ve seen so far.

They come across almost interchangeable, as sometimes certain words in English can be, but there seems to be more of a sense of movement when ‘til’ is used. Not universally – just often enough to be noticeable. Movement or transference, anyway.

Such as in:

Hun dro til Skottland. (She went to Scotland.)
Han har kjøpt det til seg selv. (He bought himself it.)
Få adgang til noe. (To access something.)

‘For’ sometimes seems used in these situations too, but more often it appears to mean more for purpose or a period. It’s more static overall.

For alltid (forever, for eternity)
Jeg trenger et bord for fire, vær så snill. (I need a table for four, please.)
For all del. (By all means.)

Sorry. I fear this doesn’t help much. I tend to rely on instinct when using ambiguous, multipurpose words like this and it’s hardly something that would be easy to look up, I imagine, with ‘for’ and ‘til’ both being words found in English, too. I bet you’d just get a load of useless results about Norwegian in general.

Plus, the example you gave (Ben går for å åpne for gjestene) does seem to have movement… but also, it states specifically the purpose he went to the door for, so it’s hard to say precisely why ‘for’ was chosen for this instance.

Either, someone Norwegian’ll come along and solve this one for us, or we’ll just have to rely on getting a feeling for it, I think.

Thank yo out anyway.

S’okay. We can muddle through together, lol. Just having to consider your question taught me something about the usage of these two words, I think.

I know this question is more than two months old already, but since I’m Norwegian, I’d figure I’d give my simple non-professional take on it:

It’s basically the difference between doing something FOR someone, and giving something TO (“til”) someone. In Norwegian, gifts and anything else you give someone uses “til”. Just as you would say

I gave the keys to John = Jeg ga nøklene til John

you keep that preposition in a sentence like this:

That gift/present is for John = Den gaven/presangen er til John

We would use “for” if it’s an action instead, like a favour, for instance. So the difference between:

Jeg kjøpte den til deg
Jeg kjøpte den for deg

is that is the first sentence means “I bought it for you” (as in a gift), while the second sentence basically means that I bought it for you as a favour. “You could have bought it yourself, but I’d figure I’d buy it FOR you, so you don’t need to buy it yourself”. In other words, the focus is on the act of buying, instead of the thing you are giving. (Slightly forced example, since the first sentence could still be used in the second meaning, if it’s obvious from the situation.)

So in your first example, the opening of the door is an action being done FOR (“for”) the guests, while in the other, the presents are things that are meant to be given TO (“til”) the children.

Jeg støvsugde leiligheten for deg = I vacuumed the apartment for you (act/favour) (lit. “dust-sucked”)
Jeg har laget mat til deg = I’ve made food for you (still an action of sorts, but the focus is on the food (a thing) and that this food is for you)

Jeg har laget mat til bestefar for deg = I’ve made food for grandpa for you
The food/thing is for grandpa (“til”), but I did you a favour (action) and made it so that you don’t have to (“for”).

I can see how it’s confusing if you’re used to “for” in both cases. I often find prepositions in languages I’m trying to learn to be some of the most confusing things.

Thank you.