If the device is new, or you have the box, you can check for the following sticker on the packaging and inserts in the box.
If you don't have the Box, you can check the Device settings from the main menu. The Non-WIFI device does not have the "Check for updates" or "WIFI" as seen on the left image below:
Under "Device Info" a device that does not have WIFI, you will see "Not Supported" under WIFI version as shown below:
The WIFI and Non-WIFI devices are exactly the same with the exception of being able to update over WIFI.