A work day is a day on which work is permitted by law without special restrictions. According to § 3 para. 2 of the Federal Leave Act (BUrlG), "all calendar days that are not Sundays or public holidays are considered to be work days".
As a result, the days from Monday to Saturday are usually workdays. In contrast, a working day is a day on which people actually work.
In most occupations of the trade and handicraft trades only Monday through Friday are working days.
In some industries, e. g. commerce, transport or the hospitality industry, however, Saturdays and Sundays are working days.