TSEW is for anyone transferring to a terminal radar facility of lvl 9 and above. You are correct in presuming that TETRA is an N90 specific course. N90 is typically a pass/fail as it is a selection factor for being able to report to N90 to enter training. TSEW is not and can never be pass/fail since it is technically a workshop, (Terminal Radar Skill Enhancement Workshop.) Now, the main difference between the two is that TSEW furthers on RTF in that it focuses on class bravo service area elements and running a final using “C to A” techniques. TETRA focuses on that but with some more small nuances that require just a bit more situational awareness during periods of high traffic load, it is debated to be an irrelevant course altogether. As for course lengths I’m not sure. Hope this helps!