Some hosts will let you setup subdomains directly from the control panel interface without talking to anyone, so i'd login there and see if it's an option. Once it's setup, the main difference is that a subdomain can have it's own document root.

Personally, i think subdomains look nicer/more professional on a business card and are easier to remember, but you're just as likely to have someone say the opposite. Same for "SEO" benefits, there is probably negligible difference between the two.