I bought a used Phantom 4, how can I tell if it’s a version 2?

Hello and good day. Thank you for reaching out. The similarities and the difference between the DJI Phantom 4 Pro V2 and with the DJI Phantom 4 is that the DJI Phantom 4 Pro V2.0 uses the same camera as the Phantom 4 Pro and is equipped with a 1-inch 20-megapixel sensor capable of shooting 4K/60fps video at 100Mbps. Also, like the DJI Phantom 4 Pro, V2.0 features a 30-minute maximum flight time and 7-kilometer long-range control. The remote controller of the Phantom 4 Pro V2.0 also supports 2.4 and 5.8GHz frequency switching, and a remote controller a with built-in screen is also available. Different from the DJI Phantom 4 Pro, the DJI Phantom 4 Pro V2.0 is equipped with an OcuSync transmission system, which allows the drone to connect to DJI Goggles wirelessly. The DJI Phantom 4 Pro V2.0 also features an upgraded propulsion system with FOC sinusoidal driver ESCs and 9455S quick-release propellers that reduce noise and make the drone more aerodynamic. In addition the remote controller of Phantom 4 Pro V2.0 is not compatible with the DJI Phantom 4 Pro, which uses Lightbridge transmission. Other accessories such as batteries, chargers, and ND filters are compatible with both the Phantom 4 Pro and Phantom 4 Pro V2.0. Thank you.

If the controller model number is GL300L - you have a V2.0
The controller of the original P4 pro is a GL300F

You can check the serial number, the serial number can also be used to check activation date, but i'm not sure if DJI would give warranty on a used drone that wasn't activated by you.

The V2.0 P4P will have winglet props, a gold DJI sticker on the top (not silver) and will be quieter in flight. The most noticeable visual difference will be the RC - the V2.0 remote has vents at the bottom as seen in this pic using OcuSync V2.0 rather than Lightbridge.