All certified woodstoves offered for sale will have a permanent and a temporary label indicating that the stoves are EPA-certified. The temporary label will also contain information that you will find useful when shopping for a new stove.
The label will tell you generally how clean and how efficient each woodstove is. However, because regulations require all new stoves to burn much cleaner and more efficiently than unregulated woodstoves, there should not be significant differences in efficiency and emissions performance among the certified catalytic models. This holds true for the non-catalytic models as well.
The label will also indicate which stoves are equipped with catalytic combustors.
Perhaps the most important information on the label you will need when selecting a stove is the heat output range. Use this information to help select the right size stove for the space you will be heating.