Economy is the set of production, consumption, supply, demand and like-wise functions put together of a region/country. Simply, when we say ‘economy of a country’ we mean every economic activity that is going on there. It is a very broad term.

Gross Domestic Product(GDP) is the sum of final goods and services produced within the country. Simply put, what we produce adds to GDP(there are many conditions, though).

Thus, GDP is only related to production. GDP is one of the many parameters which talks about economy.

- extracted from Pramod Challa's answer to 'What is the difference between GDP and economy in layman terms?', Quora as on 26th September, 2018