Thanks for your reply. However, I'm still confused. The following are selected quotes from an article on Gyroscopic instruments I found by searching the net:
Turn & Slip Indicator
"The turn needle is an electrically driven gyroscope which indicates the rate of turn"
"This type of instrument is usually found in older aircraft"
Turn Coordinator
"The Turn Coordinator is similar to the Turn & Slip Indicator. It is found in more modern aircraft. The main difference is in the presentation of the turn. A miniature airplane is used to show the bank instead of a needle"
Another article states that the T&S Indicator shows Rate of Turn only, whilst the Turn Coordinator also shows Rate of Roll.
However, what I am interested in is which of them is most reliable in an inverted spin situation