In some ways, there's not much of a contest between GW Pharmaceuticals (NASDAQ: GWPH) and Corbus Pharmaceuticals (NASDAQ: CRBP). GW's market cap is more than 10 times larger than Corbus' market cap. GW already has two approved drugs -- Sativex outside the U.S. and Epidiolex in the U.S. -- while Corbus has none.

But a smaller size and the potential for pipeline catalysts often can make clinical-stage biotechs like Corbus bigger winners than biotechs with a head start like GW Pharmaceuticals. Which of these stocks is the better buy right now? Here's how these two biotech stocks stack up against each other.

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The case for GW Pharmaceuticals

You don't have to look hard to find a big reason to like GW Pharmaceuticals. The biotech launched Epidiolex on Nov. 1, 2018, after winning FDA approval earlier this year for the drug in treating Dravet syndrome and Lennox-Gastaut syndrome (LGS), both of which are rare forms of epilepsy.

How successful will Epidiolex be? That remains to be seen. But some analysts project the drug could generate peak annual sales of $1 billion and perhaps significantly more.

This optimism stems from several factors. Epidiolex is the only drug to win approval for treating Dravet syndrome, which affects around one in 15,700 infants. Other drugs have been approved for treating LGS, but there is a considerable unmet need in patients who don't respond well to these drugs. GW Pharmaceuticals set the list price for Epidiolex to be competitive with other antiepileptic drugs.

The biotech also hopes to win European approval for Epidiolex in treating Dravet syndrome and LGS. This approval could come early next year. In addition, GW is conducting a late-stage clinical study of Epidiolex in treating the genetic disease tuberous sclerosis complex and a phase 2 study of the drug in treating another rare genetic disease, Rett syndrome.

GW has already obtained regulatory approval for cannabinoid drug Sativex in several countries as a treatment for multiple sclerosis spasticity. The biotech is pursuing U.S. approval for the drug in this indication. In addition, GW is evaluating other cannabinoid drugs in early and mid-stage studies targeting autism spectrum disorders, epilepsy, brain tumors, schizophrenia, and neonatal hypoxic-ischemic encephalopathy -- a rare disease that causes brain damage in infants.

The case for Corbus Pharmaceuticals

Corbus Pharmaceuticals' lead pipeline candidate is lenabasum. The biotech is evaluating the drug in late-stage studies for treating the rare inflammatory diseases systemic sclerosis and dermatomyositis. Corbus expects to report results from these studies in 2020. If all goes well, lenabasum could reach the U.S. market by 2021.