There's nothing inherently dangerous about ETFs. The same way that a mutual fund could hold incredibly risky or US government bonds, an ETF can too.
The major difference in ETFs vs mutual funds is that ETFs are traded like stocks during market hours. It takes a little more management because while you can place "market" orders, you really shouldn't because sometimes there are flash crashes. So you should place limit orders (ie, don't sell unless it's at least X, and conversely for buying). And because it's traded like a stock on the exchange, there is a bid/ask spread (you always pay a little more than the actual net asset value, and you always sell for a little less. For a well traded enough ETF, this is negligible).
Since the ETFs you linked are index ETFs, just go with the cheapest one, IVV, at 0.07%.