What is the basic difference between seismonasty & thigmonasty?

Seismonasty is the nastic movement towards touch but thigmonasty is specifically for the touch of insects.

The difference is that tropisms are influenced by the direction of their stimulus, while nastic movements are not. Thigmonasty or seismonasty is the nastic response of a plant or fungus to touch or vibration. It differs from thigmotropism in that it is independent of the direction of the stimulus