I don't know the Trinity exam.  Many people from Spain on italki take the Cambridge, which I have become familiar with by helping them practice for this exam.

I took the FCE test, to be honest I know nothing about Trinity exams. I think they are not used in my country. 

Hola Jesus,

I've helped a lot of people in Spain with Cambridge and Trinity exams, and I can tell you they are very different from each other. In addition, Trinity is less well known, and might be a problem if you want to work outside Spain. 

In general, they are both good exams, but the Trinity certificate includes a portfolio of writing that you must do before the exam. If you enjoy writing essays, Trinity is a wonderful ceertificate. 

Cambridge exams have more grammar (use of English), and the reading is very difficult, but the speaking in a Cambridge exam is a bit easier than Trinity, in my opinion. 

In January 2015 the scoring for Cambridge exams is changing to make the Cambridge exam more like the IELTS exam, and I think this means that the Cambridge certificate will become VERY useful for working in other countries. 

Hello Jesús, I think that if you like writing and speak with another people the Trinity exam is the best option. If you prefer study grammar and vocabulary the way is the Cambridge exam. I think that is more technical that Trinity.

Thank you all!