Cacher is the code snippet organizer for pro developers

https://www.reddit.com/r/nexus5x/comments/49sbgu/what_is_vendor_and_system_img/

Vendor usually includes custom driver specific to the device.

vendor-image VS vendor The images version is larger because it is a bit level copy. The non-image version is a file level copy. Marshmallow has verification at the block level now, so the but level copies should preserve this.