When the Prince of Orange married Ms Máxima Zorreguieta Cerruti, he was active in the military and proudly wore his Grand Tenue 1 of the Royal Netherlands Navy with the rank of a Captain-at-Sea,
see picture. Because the groom was in military uniform, other guests could opt for a military uniform as well, if wanted.
His brother Prince Constantijn never served in the military. The wedding was a day event, so he had no any option than to wear jacquet,
see picture. Because the groom was not in military uniform, all other guests came in civil too.
The same counts for his brother Prince Friso, whom also never served in the military. The wedding was a day event, so he had no any option than to wear jacquet,
see picture. Because the groom was not in military uniform, all other guests came in civil too.
It is often not a "choice" but dictated by the time and/or circumstances.