The main difference between an attache case and a briefcase is size. An attache case is larger in size, while a briefcase is smaller. This means that an attache case can hold more items than a briefcase. Another difference is that an attache case typically comes with a shoulder strap, while a briefcase does not.

The difference between a "case" and a "briefcase" lies in their specificity and structure. A "case" is a broad, generic term for any container used to protect or carry items, such as a suitcase, vanity case, or phone case. A briefcase, however, is a specific type of narrow, box-shaped case designed primarily for carrying documents, laptops, and professional tools. Historically, briefcases were used by lawyers to carry "legal briefs," giving them their name. Structurally, a briefcase usually opens into a single main compartment with various organizational pockets, whereas an "attache case" (a cousin of the briefcase) is often slimmer and opens into two distinct halves. While a general "case" might be made of any material for any purpose, a briefcase is almost always associated with business or formal environments and is typically constructed from leather, aluminum, or heavy-duty nylon with a top handle.