The Student Room Group
I did both. Scottish Highers are not equivalent to A levels but they're not as low as AS either.. they're sort of somewhere in between. To give you an idea, UCAS gives a Scottish Higher A 72 points but an AS A 60 points. Then there's Advanced Highers which are equivalent to A level points wise but generally regarded tougher (even by Oxbridge btw, to hush any controversy this might cause). Main differences: you can't resit for Highers and Advanced Highers as they're not really modular although you may sit say 2 papers for a subject. Highers don't have coursework/practical exams but just a single practical exercise which you have to pass. Grade boundaries are 75% theoretically for an A at Higher but this is often lower depending on performance (just like the whole raw marks -> ums conversion for A level). That's it really.

Scottish Highers get you into uni in Scotland but you spend a year longer than English Unis e.g. a Bachelors is 4 years.