comma with 'which' [relative adverb]: in different outcomes, which

Hey there,

I am not sure about the comma before which regarding two sentences. I think 'no comma' is correct:

Divergent capabilities for marketing departments result in different outcomes (,) which lead to a competitively difference.
They want to add value through marketing (,) which can even lead to higher costs.

I have absolutely nothing to justify this but I wouldn't use the comma in the first sentence although I would use it in the second. For me, it's simply where I would pause in saying these sentences aloud.

I think both these instances of 'which' can be replaced by 'and this' or 'and these'. I conclude that both these relative clauses are, or at least can be, descriptive rather than restrictive. I therefore think that a comma is possible in both cases. I also think a comma is helpful here as the sentences are quite long.

Technically, it's a matter of restrictive vs. non-restrictive clauses.

Divergent capabilities for marketing departments result in different outcomes, which lead to a competitive difference. (note that it's competitive, not competitively) Here the relative clause is clearly non-restrictive, so it would normally be set off by a comma (unless very short).

They want to add value through marketing (,) which can even lead to higher costs. Here the relative clause could go either way, depending on what you mean:

They want to add value through marketing which (or that) can even lead to higher costs -- means that there is some other kind of marketing which won't lead to higher costs, so it's a restrictive clause, specifying the kind of marketing that is being considered. Restrictive clauses generally don't take commas.

They want to add value through marketing, which can even lead to higher costs -- here it's a non-restrictive clause, giving additional information but not restricting which kind of marketing is being considered.