In practice, the choice between them depends on your style: if you're willing to keep an eye on the price and buy at a convenient moment, an ETF is more convenient because it trades like a regular stock on an exchange. A mutual fund is simpler for those who prefer the "buy and forget" approach - you just put money in and the manager invests it themselves. ETFs really are often cheaper on fees, and the tax situation is simpler - profits are only counted when you sell shares, not once a year like in regular funds.
But here's what people often miss: with intraday trading on an ETF, the spread (the difference between the buy and sell price) can be significant, especially if the fund isn't very liquid. For medium-term investments over 3 - 5 years, that can eat into your profits. Plus, an ETF requires you to have a brokerage account, while you can invest in a mutual fund directly without extra middlemen.
For a beginner, I'd recommend first figuring out what exactly you want - a diversified portfolio of stocks, bonds, or something specific. Then choose the format: if you like simplicity and don't want to track prices, go for a mutual fund; if you're willing to deal with a bit of hassle to save on fees, go for an ETF.