What are the key differences between allylic and vinylic compounds in terms of their chemical properties and reactivity?

Allylic compounds have a carbon-carbon double bond next to a carbon-carbon single bond, while vinylic compounds have a carbon-carbon double bond directly attached to a carbon atom. Allylic compounds are more stable and less reactive than vinylic compounds due to the presence of the single bond, which provides additional stability. Vinylic compounds are more reactive and undergo addition reactions more readily than allylic compounds.