first of all whats the difference between a trial and a tribulation.
trial: that by which something is tried or proved, a test
tribulation: oppression, affliction, tribulation, distress, straits
it would seem the duration of time involved.
A test is to firm up the steadfastness of ones belief.
A tribulation would be to correct or reprove a work of darkness that is causing a christian to stumble.
tests might be all around us in society
tribulations might be sent of god to do his work in our lives.