niallp,
they are very different.
I suggest you go to citi uni and understand your problem.
A brief description of lanter tests is writen
here.
But I suggest you try them all so you won't have any doubts!!
I'm goig for spectrolux. I've passed Nagel but in city uni, which, I've been told in portugal it's not accepted because it was made in a university..
good luck