Selecting an amplifier - a PA or LNA that seem to have similar gains and P1db
What am I missing?

Probably not much. An LNA with a gain of 40 dB will just be typically, as being optimized for NF rather than high efficiency, more power-hungry, unless also much more expensive. Also, I'd expect an LNA to have flatter gain over its operational frequency range.
Also, you need to realize that &quot;PA&quot; and &quot;LNA&quot; are labels that we put on our devices ourselves. I can call a 10 dB gain amplifier with a 10 dB noise figure &quot;LNA&quot; if I want to, nothing is going to stop me.