Investing in the stock market is one of the most effective ways to build long-term wealth, but you'll need the right investments to maximize your earnings.

There's no single correct way to invest; everyone will have unique preferences and risk tolerance. If you're looking for a low-maintenance investment that requires next to no effort on your part, an exchange-traded fund (ETF) could be a smart option.

An ETF contains dozens or even hundreds of stocks, all bundled together into a single investment. This not only provides diversification and lowers your risk, but it also means you don't have to spend time researching and buying individual stocks.

While there are countless ETFs to choose from, these two Vanguard ETFs could turn just $200 per month into $395,000 or more.

1. Vanguard S&P 500 ETF

The Vanguard S&P 500 ETF (VOO -0.74%) tracks the S&P 500 index. It includes stocks from 500 of the largest and strongest companies in the U.S., ranging from tech giants like Apple and Amazon to well-established brands like 3M and Procter & Gamble.

S&P 500 ETFs are among the safest types of investments, perfect for risk-averse investors. The index itself has a decades-long history of surviving even the worst market crashes and recessions, so it's extremely likely this ETF will recover from future volatility as well.

Despite its relative safety, this fund could also help you earn a lot of money over time. Historically, the S&P 500 itself has earned an average rate of return of around 10% per year, meaning the annual highs and lows have averaged out to roughly 10% per year over decades.

If you're investing $200 per month while earning a 10% average annual return, here's approximately how much you could accumulate over time depending on how many years you invest:

Data source: Author's calculations via Investor.gov.

To reach $395,000 in total savings, you'll need to invest consistently for 30 years. But if you're able to invest more per month or give your investments more time to grow, you could earn substantially more, potentially even reaching $1 million.

2. Vanguard Growth ETF

The Vanguard Growth ETF (VUG -1.01%) contains 235 stocks from a wide variety of industries. Although around half of the fund is made up of stocks from the tech sector, this ETF still provides plenty of diversification that can help limit your risk.

The biggest difference between a growth ETF and an S&P 500 ETF is that a growth ETF contains stocks with the potential to earn above-average returns. While an S&P 500 ETF is designed to follow the market, a growth ETF is designed to beat the market.

This particular ETF, though, can help maximize your returns while still reducing risk. Around half of the fund is made up of blue chip stocks (such as Apple, Amazon, and Microsoft), while the other half is made up of stocks from up-and-coming companies.

While smaller stocks tend to carry more risk, they also have greater potential for explosive growth. Meanwhile, the behemoth blue chip stocks might see slower growth, but they're also far less risky.

Over the past 10 years, the Vanguard Growth ETF has earned an average rate of return of just under 15% per year. But to play it safe, let's assume your investment only earns a 12% average annual return. If you're investing $200 per month, here's approximately how much that could add up to over time:

Data source: Author's calculations via Investor.gov.

If you invest consistently for 30 years, you could accumulate around $579,000, compared to $395,000 with the S&P 500 ETF. And with just a few more years, you could nearly double your total earnings.

Which ETF is right for you?

Whether you choose to invest in the S&P 500 ETF, the growth ETF, or both depends on your personal preferences.

Growth ETFs are inherently riskier, because fast-growing stocks tend to be more volatile than their more established counterparts. There are also never any guarantees in the stock market, so there's always a chance this type of ETF might not actually beat the market at all.

S&P 500 ETFs are generally safer, but again, they often earn lower returns than a growth ETF. For some people, that's a worthwhile trade-off for an investment that's very likely to recover from downturns and see positive returns over time. But it won't be the right fit for everyone.

Where you choose to invest, then, will depend on your priorities. Both of these ETFs can be fantastic options, and with consistency and a long-term outlook, either one could help you earn hundreds of thousands of dollars or more.