The big difference is that I worked with big corporations while working at large design agencies, but since going freelance have worked primarily with smaller clients. A big corporation like Nintendo would only seek out a freelancer if it was someone very famous for a unique style (such as Shepard Fairey or Ghostshrimp). Bands like to use freelancers like me because we’re cheaper and faster and involve far fewer meetings and offices; Yes management can call me on a Tuesday and tell me they need a poster for Thursday and I can turn it around, but you can’t pull that crap on a 100-person design agency.
When I was creative director at a design agency, we mainly worked with Procter & Gamble, and while they are a huge scary corporation with offices that look like Death Star hallways, no joke, the individual brands are like little mini-companies – I spent a lot of time becoming intimately familiar with Folgers, Mr Clean, Febreze, Swiffer, and five years of my life was sunk into Home Made Simple – and I did go back & do a little freelance for them afterwards, because the individual brand managers knew me & needed some extra help here and there. But generally big companies use big agencies, small groups/individuals use freelance designers.