You are more likely to hear the word "downturn" in connection with a specific market than about an entire country. Most markets have what is known as a market cycle. You don't measure how successful a business is by what they make in a day, but over a measurable period. Depending on the type of business that could be a year, but not necessarily so. An example of this is the housing market which is affected by many other things - interest rates generally reflect the overall financial situation in a country, these in turn affect mortgage rates, which dictate whether some people can afford to buy houses, and that in turn has an effect on house prices and how much money estate agents / realtors can make. Sometimes the expression "downturn" can be used to mark a period of decline in a particular market such as housing, but this is not always a negative thing - it can be seen as just part of that industry's market cycle. Again, in the housing market, most people have to be able to afford to move and buy a new house in order to want to sell the one they have, and so it is quite expected for the market to have periods of downturn followed by an upturn. Periods of downturn in the housing market can often result in upturns elsewhere - for example, if people cannot afford to move to a larger house they are more likely to invest money in extensions to the house they have, which is good news for the building industry.
A "recession" is something that is usually said about an entire country, when multiple factors may have affected public spending across multiple markets. It is usually a nationwide recession that prompts interest rates to be lowered to encourage spending.