I guess, to sum up the difference, students here, at the age of 16, decide to go on the university path, or the trade school path (e.g.,to be a mechanic, plumber, computer technician--vs. a computer science major--etc.) path. I've noticed there's some confusion when talking to Brits about engineering degrees--a couple I've spoken with confuse a two-year electronics degree (the equivalent of maybe a two-year associate's degree in the States, or a trade school certification) with that of a four-year electrical engineering university degree (EE is probably the hardest major there is). Also, it takes three years to get a bachelor's here, whereas it takes four years in the States (typically 120 credits or "hours" required, breaking down into an average of 15 a semester for eight semesters). Anything else I'm missing? So A levels go toward the uni path, and O toward the trade school path?
Formica, another thought: The rule of thumb I've always heard is to keep your resume (actually, with a Ph.D., you have the right to call it a CV, by U.S. standards) to one page per 10 years of work experience. Obviously, depending on the position you're applying for, a separate list of publications would be due, as well. I'd include that with the resume, but not provide a list of references unless asked (the old "References available upon request"). Also, I see nothing wrong for you to say, IF asked why you want to live here, that your family is here, you've always been interested in England, etc. BUT be sure to include a professional slant in your answer: something about the job potential you see here, what you could offer, etc.
Also, it's smart of you not to let an interviewer know that your decision to move here hinges on your getting the job. Giving personal reasons is usually a turnoff to an employer. (It's akin to the rule about asking for a raise--you'd never tell your employer you were broke, had kids to feed, had debt collectors knocking on your door--that's not their problem; it's yours. You ask for a raise by having documented proof at hand about your achievements since the last time your salary was assessed.) Okay, so much for my six cents worth.