Agitating To move a certain liquid, powder, or other highly viscous material in a vessel in order to keep it in a homogenous, constant state with equal temperature throughout.
Blending To bring different liquids, oils, fragrances, beverages, etc. from the same physical origin together to refine the product. For example, creating a high quality motor oil by blending it with a certain mineral oil, or creating an innovative “Armagnac” beverage by blending different brandies and cognac.
Mixing To bring completely different liquids, powders, ingredients, or batches from different lines in a vessel and mix them into a completely new product and/or state that can flow further down the manufacturing line. For example, combining different fruits, ice, water, and sugar to create a smoothie beverage.
Stirring This is the movement in general. It can be through a propeller or other agitator, or by hand with a stirring utensil.