They Care About Wrinkles
Millennials truly cannot be bothered by a wrinkly shirt. Sure, they may break out the iron for an important job interview, but to iron an everyday shirt? No, way. Boomers won't hesitate to point it out, though.
Email is a Main Source of Communication
Boomers commonly use email as their main source of information. Oftentimes, they sign off in caps lock. If they aren't using email, then they're using Facebook. The caps lock is still on.