That photo is very poor - but I'll have a stab....
The key difference here is that you are using a mono microphone with a balanced xlr output running into a stereo unbalanced recording device. You don't need to understand the difference between balanced and unbalanced - but you will need an understanding of how the different plugs are wired by convention.
Conventionally, the XLR connector is designed to have a live, neutral and ground to carry a single signal between devices. If you were using a cd player in stereo, you would have 2 xlr outputs, 1 left and 1 right. The 3.5mm connector is of TRS type - what this means, and you can see in your photo, is Tip Ring Sleeve, looking at your photo you can see the black isolator rings (2) thus giving 3 distinct parts of the plug. Your recording device is stereo and therefore is expecting the following from a TRS connector, live signal 1 on the Tip, live signal 2 on the ring and a common negative on the sleeve. This will allow 2 separate signals to be transmitted on a single plug, in this case a left and right channel.
In your set up, as you are using a mono microphone, there is only one signal to be recorded. Your plug is wired so that the ground is the sleeve and the signal (live) from the xlr has been combined on both the tip and ring of the TRS plug. This means that when recording the device sees the same input on both L&R channels in your recording device.