Can someone explain the change and the reason for it to me? Why change from calling them Technical Releases to calling them Technical Specifications? (At least that's what I was told it meant)
In C++, ISO/IEC TR 19768:2007 (better known as "TR1") was not normative: it was just a set of boost libraries and C99 components put together in a form that compiler vendors could test drive for the future C++11 standard inclusion. ISO/IEC TR 18015:2006 (the Performance TR) was just a prose document debunking a few common myths.
ISO/IEC 29124:2010 and ISO/IEC TR 24733:2011 are other non-normative C++ TRs (special math functions and std::decimal) which are essentially test-drives of future library components.
TS, on the other hand, is essentially a preview of a standard, ISO requires that every TS either becomes a part of an international standard or is withdrawn in 6 years.