Final answer:
One similarity among states in East and Southeast Asia is their historical colonization by European powers, while one difference is their economic development.
Step-by-step explanation:
One similarity among states in East and Southeast Asia is their historical colonization by European powers. For example, both Vietnam and Indonesia were colonized by the French, while the Philippines was colonized by the Spanish.
One difference among states in East and Southeast Asia is their economic development. For instance, Singapore has become an economic tiger with a highly developed economy and a major financial center, while East Timor, as the newest independent country in the region, is still in the early stages of economic development.