They are both adjectives.
pertaining to the production, distribution, and use of income, wealth, and commodities.
of or pertaining to the science of economics.
pertaining to an economy, or system of organization or operation, esp. of the process of production.
involving or pertaining to one's personal resources of money: to give up a large house for economic reasons.
pertaining to use as a resource in the economy: economic entomology; economic botany.
affecting or apt to affect the welfare of material resources: weevils and other economic pests.
avoiding waste or extravagance; thrifty: an economical meal; an economical use of interior space.
(dictionary.com can be useful to quickly check differences in meaning)
If this is not helpful, you may need to provide more context so that someone can assist you to decide which one to use.