Symbol rate offset estimation
I'm not sure if there are clear definitions for each term but here are my suggestions:

Symbol rate offset is the difference between the symbol rate entering a receiver and the symbol rate used by the demodulator. It could be measured in Hertz or parts per million (ppm).

Symbol timing offset is the difference between the time that a symbol should have been sampled and when it was sampled. It could be measured in seconds or fractions of the nominal baud duration.

Sampling clock offset is symbol rate offset multiplied by samples per symbol.

John