What is the difference betweenprepared improvisation and spontanious improvisation?

Prepared improvisation involves having some pre-planned elements or structures in place before beginning the improvisation. This could include predetermined themes, melodies, or chord progressions that the improviser can draw upon during the performance. Spontaneous improvisation, on the other hand, is done entirely on the spot without any prior preparation. The improviser relies solely on their creativity and ability to think on their feet. While both approaches have their merits, prepared improvisation often provides a foundation for exploration and experimentation, while spontaneous improvisation encourages a greater sense of risk-taking and immediacy.