How can you recognize a plane from the inside, when you are already sitting as passenger? In particular, is there a way to understand if you are inside a Boeing or an Airbus?
There are many details to recognize, for example: The handle that locks the doors.
Image is a still from this video
Another way is to read the safety card, on them, you can read clearly if you are on a Boeing or Airbus, and on which type as well. The first picture is a typical Boeing's door, and the second, an Airbus'. (source internet pictures from different types of handles) On Airbus A32F, when the landing gear extends, the exit lights will turn on. The cabin interior differs from company to company, however the cockpit is unique, but nowadays, passengers are not allowed to visit the cockpit during the flights. If you seat on the seats, from where you can identify the winglet, they could give you some tips, most of the Airbus A32F have shark winglet, but it is changing, however, scimitar winglets are typical from New generation Boeings 737.
When entering the plane have a look at the front door's frame. Airbuses have a sign showing when the door / plane was manufactured. I always check this sign just to know how old the plane is...
This placard is required by 14CFR45.11(g)
(g) The identification plate described in paragraph (a) of this section may be secured to the aircraft at an accessible location near an entrance for—
(1) Aircraft produced for—
(i) Operations under part 121 of this chapter,
(ii) Commuter operations (as defined in §110.2 of this chapter), or
(2) Aircraft operating under part 121 of this chapter and under an FAA-approved continuous airworthiness maintenance program; or
(3) Aircraft operating in commuter air carrier operations (as defined in §110.2 of this chapter) under an FAA-approved continuous airworthiness maintenance program.