OK, thanks a lot !They are not interchangeable, but their meaning overlap partially.
The core meaning of 'selskap' is 'company', and this includes a trading company and a social company/gathering. A gathering can be also a feast, hence in such occasion the meaning overlaps with feast (fest).
'Fest' means only 'feast'.
These sentences are not quite comparable. The noun is in the indefinite form in the first sentence, and in the definite form in the second.Mine venner har selskap på lørdag.
Mine venner har festen på lørdag.
Thank you for the explanation. Much appreciated!I can add that although both "selskap" and "fest" can be translated as "party", there is a nuance: "selskap" has a more limited use, and is mostly used for more formal occasions.
If it is an informal gathering, you should use "fest" - but "fest" can also be used in more formal contexts (for example "bryllupsfest", (wedding party)) .
These sentences are not quite comparable. The noun is in the indefinite form in the first sentence, and in the definite form in the second.