Investing is long-term and involves low risk
First, simply investing isn't "low risk" but rather involves lower risk when compared to trading. However, both of them work just fine. One main advantage of simply investing rather than trading is that you don't need any special knowledge, all you need to do is make the purchase. But on the other hand, not only do you need to have knowledge of trading, you have to be good at it and be able to make your own call. So, if you have the knowledge to trade, give it a shot to see how good you are. If it's not so good, you can learn more or stick to simply investing.
Aside from knowledge of trading, you also need to have more experience. Even if you have enough knowledge, you can't simply gain profit by only that.
But yes, if he's unsure what to choose between trading or investing, give it a try to experience what he prefers. Once he tries, he will know what is better for him.
There are many things that we have to prepare before starting to trade so that we can get profits from the trades that we make. By having the knowledge, we can already try to trade, but if we are just starting out, it would be better if we can try with a little capital so that if we get problems in trading that we do can still be fixed and if we have a lot of experience with little capital and we can try it with the savings we have.