Chaityas represent Mahayanism and Stupas Hinayanism
Chaitya is a r eligious ter m, while S tupa is an architectural term for a mound containing a relic of the Buddha and later on of leading Buddhist Saints
Chaitya is a place of prayers/worship while Stupa is a funeral monument
Chaitya were constructed by the monasteries while Stupas were constructed by the kings and the rich merchants