The Phishing IQ UK Edition uses email messages that seem to come from companies British citizens would be aware of, such as Lloyds and Halifax. The Phishing IQ Test II is geared more towards Americans with email messages that seem to come from US-based companies such as Chase and Washington Mutual.
The tests are little more difficult than scanning through your typical inbox inundation because obviously if you get an email from a company whom you do no business with that asks you to login to your account then it's highly likely that it's a scam. You don't have that advantage while taking MailFrontier's test since the messages obviously aren't in your inbox. So the tests might give you a better measure of your scam spotting ability.