Whuy picture/file url with ?v=

[creationacc]

Why 2 url for 1 file ?

Example : 

• https://cdn.shopify.com/s/files/1/0111/3663/0884/files/nameXXXX.jpg
• https://cdn.shopify.com/s/files/1/0111/3663/0884/files/nameXXXX?v=1581861125

Which is better ? What difference ? Both are well displayed.

Thank you for you help