LOL. From a practical standpoint truesight was always rather poorly defined. The MM1 version simply stated that the creature could see invisible creatures in its LoS. Blindsight is different, and has actually changed a decent amount between MM1 and RC, though the end result is usually about the same. I think it is rather odd the way RC claims that truesight is the same as blindsight. They really don't do the same thing. The real problem with truesight is the definition was always rather ambiguous. You can see invisible creatures within range and LoS but it doesn't really clarify how this works, does it require light? IE is it a totally separate sense or is it just a quality of the creature's existing vision?