Updated: Oct 23, 2018
Professional attire almost always means Suits (with tie) for men, paired with a solid-colored dress shirt. Suits, pants suits or dresses with a jacket for women. Neutral colors and conservative footwear for all.
Appropriate business casual dress typically includes slacks or khakis, dress shirt or blouse, open-collar or polo shirt, optional tie or seasonal sport coat, a dress or skirt at knee-length or below, a tailored blazer, knit shirt or sweater, and loafers or dress shoes that cover all or most of the foot.
A casual dress code means that employees are permitted to dress in comfortable, informal clothing such as jeans. Keep in mind that casual does not mean you can wear just anything.