You won't find a lot in common between Aurora Cannabis (NYSE:ACB) and MariMed(NASDAQOTH:MRMD).

They both operate in the cannabis industry, but they differ in multiple ways, including geographical focus, size, and stock performance.

On the last category, MariMed has been the clear winner so far in 2018.

Its stock has more than quintupled while Aurora's share price is close to where it started the year.

But which of these two marijuana stocks is the better pick for investors now? Here's how Aurora Cannabis and MariMed stack up against each other.

The case for Aurora Cannabis

There are three key arguments for buying Aurora Cannabis stock:

1. The global marijuana market is going to be huge.
2. Aurora has the production capacity to be a major player in this market.
3. Aurora has the distribution channels to be a major player in this market.

Let's look at each of these arguments in more detail.

Is the first statement true? It depends on what you think "huge" means. Regardless of the measuring stick you use, the global marijuana market appears to be on course to expand dramatically.

Arcview Market Research and BDS Analytics project the global marijuana market will reach $32 billion by 2022, more than triple the market's size last year. Some industry participants project that the global marijuana market will grow much larger than that over the next 15 years. A market size of $150 billion is on the low end of these projections.

The second key argument for Aurora isn't as subjective. Aurora expects to have an annual production capacity of 150,000 kilograms (330,693 pounds) by the end of this year. It will be able to grow more than 500,000 kilograms per year by the middle of 2019, making Aurora the largest marijuana grower in terms of capacity.

What about Aurora's distribution channels? The company appears to be in good shape in the Canadian recreational marijuana market. Aurora claims supply agreements with nine provinces that together are home to 98% of Canada's population. 

Aurora's international distribution channels seem solid as well. Germany ranks as the most important of these international markets. The company's Aurora Europe subsidiary is based in Berlin and is spearheading efforts to supply medical marijuana to several European markets. Aurora is also active in other countries, including Australia, the Cayman Islands, Colombia, and Malta.

There's also the possibility that Aurora could significantly expand its distribution channels by partnering with a major company outside of the cannabis industry. The company has reportedly been involved in discussions with Coca-Cola and is widely viewed as one of the top candidates to be a potential partner for Diageo.

The case for MariMed

Since we looked at three key arguments for buying Aurora Cannabis, let's take the same approach for MariMed. Probably the three main reasons to buy MariMed stock are:

1. The U.S. marijuana market is where the most money is being made.
2. MariMed is one of the best-positioned companies in the U.S. marijuana market.
3. MariMed has significant potential for growth.

The first statement is indisputable. Of the $32 billion that Arcview Market Research and BDS Analytics project in global marijuana sales for 2022, most of it -- $23.4 billion -- will be generated in the U.S.

It's also hard to argue that MariMed isn't one of the best-positioned companies in the U.S. marijuana market. MariMed develops medical cannabis production facilities that it leases to customers. It also helps marijuana-related businesses in the U.S. obtain state licenses. In addition, the company markets its own brands of cannabis products. 

MariMed has seen its sales skyrocket as medical marijuana markets begin to mature in the five states where it operates. Investors have recognized the company's potential, with MariMed rising quickly to become the third-biggest U.S.-based marijuana stock. 

And MariMed appears to have tremendous growth prospects. One of the five states where it currently has operations -- Massachusetts -- is likely to become one of seven states with cannabis markets exceeding $1 billion annually by 2022. The company is also planning to expand into Pennsylvania, New Jersey, Michigan, Florida, and Ohio. Together, these additional states should claim total annual marijuana sales of close to $4 billion by 2022.

Better marijuana stock

The cases for both Aurora Cannabis and MariMed seem to be fairly solid. So which is the better marijuana stock?

Aurora's market cap is currently 10 times larger than MariMed's. But Aurora can't currently compete in the U.S. -- the world's largest marijuana market. MariMed can. My view is that these two factors make MariMed the better stock right now.

However, marijuana remains illegal at the federal level in the U.S. MariMed faces the risk of a potential crackdown on cannabis-related businesses. It also could see increased competition. 

While I'd give MariMed the nod over Aurora Cannabis, I wouldn't call the stock a definitive buy at this point. There are other marijuana stocks that, in my opinion, present even better risk-reward propositions.