Just the ETF (in US/HK), it can already let us expose to many thing, from stock to commodity, real estate.
Some of them can provide FX hedged return. I remember wisdomtree provide FX hedged return on NKY or European index (with respect to USD).
The good thing of it is liquidity and transparent.
Also, there is some monthly dividend paying ETF which provide us regular cash flow as well.
Of coz, before investing it, we also need to do deal diligence.
Also, we can play on cryptocurrency which i treat it as mark six deal.
ETF is exchanged traded fund which is passive managed fund and listed in exchange. Unlike traditional fund which has high management fee and long settlement time, etf has lower transaction fee (do not have performance fee) and traded like stock in exchange. So more liquid and faster settlement than traditional fund.
The risk is not the same.
ETF can provide lot of different payoff / underlying asset that stock cant.
Eg 2800: buy 1 lot = long basket of stock. i am not expert in stock trading, so I do not like to have concentration risk. basket of hsi stock can help me to diversify the risk and the basket is updated periodically.
TLT/TBT: Allow us to long/short the US treasury
FAZ/FAS: allow us to expose the risk to basket of financial institute
GLD: allow us to take gold position
VIXY: allow us to long the VIX.
PFF: provide monthly dividend and expose to US preference share
HEDJ: USD FX hedged ETF expose to Europe equity index. It was great deal when EUR started QE. QE effect will depreciate the currency and push the asset price. It provides FX hedged exposure to equity market which exactly what we want. Anyway, it is water tail already.
etc etc
Of coz, as i always like to say we need to study the detail like liquidity, expense ratio, track error before buying. Above is just a sample that what etf can provide but does not mean that they are good (as i have not studied all of them).