The stock market has been thriving in recent months, and it's giving many investors hope that perhaps the worst of this downturn is over.

The S&P 500 is up by more than 22% from its lowest point in October 2022. According to some experts, this signals the beginning of a new bull market. However, others believe that we won't officially be in a bull market until the S&P 500 reaches a new all-time high.

Regardless of whether this is technically a bull market, now is a fantastic time to buy. Prices are still lower than they were when the market peaked. Here are two unstoppable ETFs to load up on right now.

1. Vanguard S&P 500 ETF

The Vanguard S&P 500 ETF (VOO 1.00%) is a safer option for those concerned about volatility. Though the market has been surging recently, many investors are still worried about a long-awaited recession hitting later this year.

This type of ETF tracks the S&P 500 index itself, so it includes all the stocks within the index and aims to mirror its long-term performance. These stocks are from 500 of the largest, strongest companies in the U.S., so if there's any investment that can survive a recession, it's the S&P 500 ETF.

It's also far more difficult to lose money with this investment than it is to make money -- if you're a long-term investor.

Analysts from Crestmont Research examined the S&P 500's rolling 20-year returns over the last century. They found that regardless of when you had invested in the S&P 500, you'd have earned positive total returns as long as you held your investments for at least 20 years.

In other words, no matter what the future holds for the market, an S&P 500 ETF is almost guaranteed to see positive returns over time.

Also, the Vanguard S&P 500 ETF, in particular, can be a smart option because of its rock-bottom expense ratio of just 0.03%. This is far lower than most other ETFs, and it could save you thousands of dollars in fees over decades.

2. Vanguard Growth ETF

One of the downsides of the S&P 500 ETF is that it can only earn average returns. It's designed to follow the market, so it's impossible for it to beat the market.

The Vanguard Growth ETF (VUG 1.82%), however, balances risk and reward to create a relatively safe investment with the potential for higher-than-average returns. This ETF includes 240 stocks from a variety of industries, though around half of the fund is made up of stocks within the tech sector.

Historically, this fund has managed to outperform the market. It's earned an average rate of return of nearly 14% per year over the past 10 years, compared to the Vanguard S&P 500 ETF, which has earned a roughly 12% average annual return in that time. While that may not sound like much of a difference, it can add up to tens of thousands of dollars over time.

A particular advantage this fund has over many other growth ETFs is its balance of blue chip stocks and smaller, high-growth stocks. Around half of the fund comprises stocks from behemoth corporations such as Apple, Amazon, Microsoft, and Nvidia. But it also has dozens of stocks from smaller companies with the potential for explosive growth.

This can help provide a healthy mix of risk and reward. The blue chip stocks are generally safer and more likely to recover from downturns. The smaller stocks carry more risk, but if any one of them goes on to become a stellar performer, you could see significant returns.

We may or may not officially be in a bull market just yet, but it's still a fantastic chance to buy. With the right investments, you can set yourself up for substantial earnings over time.