Don't get confused OP why did the majority choose to invest in Bitcoin rather than trading, it is because trading is too risky, stressful, and can't assure a profit. Unlike investing and holding, as long as you are buying low and selling high, profit is certain. But in trading, committing mistakes will end in tragic losses.
In both trading and investing, if you buy low, sell high, you get profit. If you can do it, you will have good trading and investing ROI.
The bottom line for biggest difference and challenge between trading and investing is psychology.
With trading, you get more psychological challenge from market price movements, news, fud that can force you to do bad trading decisions. With investing, you will less likely be affected psychologically because you have good knowledge, strong belief to hold you bitcoin. You won't get loss if you don't sell your bitcoin and fortunately Bitcoin recovers with time and makes new all time highs with new bull runs, historically so far.