formal > business formal > business casual > casual
Companies will require employees to wear business formal in corporate or financial environments, executive and management positions, or when interacting with high-caliber customers.
Business casual is more common in small cities and among mid- and entry-level employees. Some business formal companies have Business Casual Fridays.
When in doubt, it is better to overdress than to wear clothes too casual, so as not to be reprimanded by the suits.
"Dress for the job you want, not the job you have."
Business casual: Sweater, collar without a necktie, polo, vendor swag, blouse, black/brown/navy/gray trousers, pressed khakis.
Casual: Dockers, denim jeans, shorts, t-shirts, linen.
Yourself: Yeah dude, I'm sportin' business casual over here now.