Many get these
confused, but is easy to tell the difference once you
understand.
The term "sideloading" is very similar to the more common terms
"downloading" and "uploading," and it is much easier to
understand what sideloading means if you are already familiar
with those terms. Sideloading does not make use of the internet,
it requires you to use some other method to transfer files. This
can be accomplished with a physical connection between the two
devices, like a USB cable, or via a wireless method like
Bluetooth or Wi-Fi. If the mobile device has a memory card slot,
sideloading can also involve copying files from a computer to an
SD card and then inserting the card into the mobile device.
Downloading involves transferring a file from a remote location,
like the internet, to a local device like your computer.
Uploading is the opposite, since it involves transferring a file
from a local device, like your computer, to a remote location
like a file hosting service on the internet.
Bottom line, Think of the internet as a cloud. You upload to
the cloud and you download from the cloud. Think of another
device sitting beside yours. You sideload from it.