Kinetic control in reactions of conjugated dienes refers to conditions under which the reaction products form faster, typically at lower temperatures, and are governed by the activation energy barriers of the reactions. The products formed under kinetic control are not necessarily the most stable, but they are the ones that form the fastest.
Thermodynamic control, on the other hand, is observed at higher temperatures, which allow the reaction to reach equilibrium. Under thermodynamic control, the reaction yields the most stable products, regardless of the rate at which they are formed. This is because higher temperatures provide the energy necessary for the system to overcome activation energy barriers and allow for the interconversion between less stable and more stable products.