The reason I'm asking is - "T480" is the last nicely modular ThinkPad with removable external battery. Which means if you get a used one and need to replace the battery, it's literally a 2 second job - you push a button, slide it out, and slide the new one in :)
The "T480s" though is a slightly smaller version with only an internal battery, like all newer ThinkPads, which not everybody will be comfortable with.
And yeah, I have 2 T420s-s and 3 T480's around me today and love them :-)