I find that it is usually easier to understand products from the manufacturer's website or catalog than from Amazon or (worse) eBay ads:
Both serve the same function, to be an air admittance valve, and are from the same manufacturer.
The second one seems to be their basic model; it's not even listed among their air admittance valves, but as an accessory to the box it could be mounted in. Besides not coming with an adapter, it may also not have as much airflow capacity, or may take more pressure difference to open. Given that it's buried in a cabinet, I would choose the better one...