We'd say "vache" when it comes to milk or the female, but all "vache" are "boeuf".

Boeuf is used when the gender does not mean much (like for meat).

Cochon and porc are both used for the live animal, and both used for the food as well (cochon is a bit less used for food, but still common enough).

Boeuf and vache aren’t really synonymous as another commenter pointed out