Here is the picture that did not appear in your post.
The difference between the western ribbon snake and the eastern ribbon snake is the two little light dots on the top of the head. These are called "parietal spots" if I remember correctly, and these spots are also not found on most garters. Therefore, with this picture, you have a western ribbon snake. It is a relative of the Thamnophis, and has many similar habits and foods.
I hope this helps.
It is very common for pet stores to identify their garter and ribbon snakes incorrectly, and the term "Garden Snake" is a frequent mistake that they make also.
