Pricing & Positioning
What does $90 buy? The enclosure and the antenna. The U7 Pro Outdoor ($279) lists IPX6 weatherproofing, or IP67 with its cable-gland door kit, a directional internal antenna, 465 m² of coverage and a 60 °C upper limit. The U7 Pro ($189) lists none of those, and the same six streams and data rates. (U7 Pro Outdoor specs)
Most matchups on this site come down to a radio or a port. This one does not, because the two sheets agree on every data rate, stream count and client rating. In fact, the question here is not which access point is better. It is where the access point is going to be bolted.
Accordingly, the $90 is easy to judge. It is a 48% premium for a housing that survives rain, an antenna that throws signal in one direction, and mounts for a wall or a pole. Indoors, none of that is worth paying for. Outdoors, all of it is the point.
The U7 Pro is one of the nine ceiling APs this site tracks. The Outdoor sits apart from them, built for the weather. The Access Points hub lists the whole category. Additionally, how to choose a UniFi access point covers the indoor ceiling range in full.

