Mac Hard Drive Testing Tools and SMART Analysis
SMART testing is of limited value in many cases, and cannot often predict failure of a hard drive. This is because different hard drive manufacturers implement different parts of the spec and (as you mentioned) different software and OS manufacturers look at different pieces of the spec in interpreting the SMART status.

Beyond that there are certain mechanical issues that can be difficult or impossible to predict. If your hard drive is tapping now, there are many things that could've caused the mechanical failure and it is hard to say if SMART had a way of knowing about it beforehand.

SSDs can and do support SMART. Rather than explaining, this Server Fault thread explains it quite well.