Say you've downloaded something music from the internet to your HDD. That's downloading because you take it from an external source to a local point.
You transfer it to an mp3 player. Could this technically be referred to as an upload, since you're taking it away from the PC, or is it strictly a transfer since it's a direct link to a physical drive?
Likewise, transferring footage from a camera to the PC. Is that uploading since you're taking it from a remote point to local, or can it only correctly be called a transfer?
Does it only become an up/download if it's being transferred from an external network, and everything within the local network is a transfer?
I've always called them transfers just because it feels more... proper, but I'm asking for technicalities.