They're involved in the finance system, traders simply focus on short term target and they need to risk careful
Investors are more focused on long term goals they buy and hold for a period of time when it is suitable for them
Traders are more focused on trying to make fast profit from the market; they don't want to hold for long. They study the market and move from one pair to the other as long as they can get something attached to their money. Some of them are still regarded as investors since they use their money to trade whatever asset they trade. At the end of the day, they are all targeting to get profit.