Differentiate between parenchyma and sclerenchyma tissues based on their cell structure and functions.

Parenchyma cells are living, thin-walled, and loosely packed with large intercellular spaces. Their primary functions include storage of food, photosynthesis, and secretion. Sclerenchyma cells, on the other hand, are dead, thick-walled (due to lignin deposition), and tightly packed without intercellular spaces. Their main function is to provide mechanical support and rigidity to the plant.