Photo: Lost City Museum
Wikipedia: Yucca = a plant of the agave family with stiff swordlike leaves and spikes of white bell-shaped flowers that are dependent upon the yucca moth for fertilization, found especially in warm regions of North America
Agaves and Yuccas
Hunker.com – Both plants are succulent and grow from a rosette. The agave typically has sharp spines on the leaf edges whereas the yucca has none. Yucca plants also have thinner, straighter, and less succulent leaves than agaves and with time produce trunks.