General term for what one wears, including style and overall appearance. Slightly more formal than 服.
Go to the interview in proper attire.
彼女はいつも服装に気をつかっている。
She always pays attention to her clothing.
I straightened up my attire before the interview.
After hours of work, my clothes ended up looking disheveled.
Please come to this party in casual attire.
She's always mindful of how she dresses.
着衣 is a formal/clinical term for the literal garments on one's body, while 服装 refers more broadly to one's overall dress or appearance, including style.
transvestite; cross-dresser