Public goods and common resources differ primarily in terms of rivalry in consumption.
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Public Goods: These are non-excludable and non-rival in consumption. This means that individuals cannot be effectively excluded from using them, and one person's use of a public good does not diminish its availability for others. Examples include national defense, public parks, and street lighting.
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Common Resources: These are also non-excludable, but they are rival in consumption. This means that while it is difficult to prevent individuals from using them, one person's use of a common resource does diminish the quantity available for others. Examples include fisheries, freshwater, and forests.
Based on this understanding, the correct distinction is:
Both are non-excludable. Public goods are non-rival in consumption. Common resources are rival in consumption.