"Rye bread is not boiled."

Translation: Rugbrød koges ikke.

[chilisincarne]

Why can you not say: "Rugbrød er ikke kogt"

[Euhan1]

This could be another translation - I guess.

They do mean different things though but the ambiguity is in the English.

Rugbrød koges ikke. - Rye bread [is not meant to be | is not usually] boiled.

Rugbrød er ikke kogt. - Rye bread has not been boiled as part of its manufacturing process.

I hope this might be helpful, my vegetarian friend.