​​At a conference or event, the main speech is often called th | English as a Foreign Language

​​At a conference or event, the main speech is often called the keynote, and the person who gives it is the keynote speaker. Those things are planned far in advance. On the other hand, an impromptu speech is given spontaneously. For example, you might stand up and give an impromptu speech at your friend’s wedding – you hadn’t planned it ahead of time, but you felt inspired at the moment to address the group.
An eloquent speech is one that uses words very effectively. Someone could also give an impassioned speech meaning the speaker has a lot of emotion, or a rousing/stirring speech meaning the speech inspires emotion or action in the listeners.