Technically speaking, earbuds are not earphones, as they don't enter your ear canal. Instead they sit just outside of it, where it's easy to become loose and cause problems when it comes to accurate stereo imaging (in which both ears get the same amount of audio) and bass response. Earphones, meanwhile, fit in the ear canal and form a seal inside your ear, blocking outside noise while piping sound directly into your ears. They're much smaller and lighter than headphones, since they don't need to fit on or over your ears and don't require any outside support (though some have stiff wire sections or flexible fins to keep them in place without getting in the way). Plus they won't mess up your hair.
That said, the term earbuds has become synonymous with earphones and in-ear headphones, so the difference is ultimately academic. Whatever you call them and whatever they say on the box, you should look for earphones that form a good seal inside your ear with silicone or foam eartips. They'll sound much better than plastic-covered drivers cupped against your ear canal. Source: PC NEWS
Earphones can connect to your smartphone through a 3.5mm cable or wirelessly over Bluetooth, depending on the model. Wired earphones are generally less expensive, and you don't need to worry about keeping them charged. Bluetooth earphones are more convenient because you don't have to physically connect them to your smartphone, but they need battery power to work. For the most part, you won't find a 3.5mm port and removable cable on Bluetooth earphones; when they're out of power, they're out of commission until you charge them again.
There's also true wireless earbuds, which we also call wire-free. These are essentially Bluetooth earphones, but with no cable connecting the individual earpieces. It took a solid year for the bugs to get shaken out of this category, with issues like short battery life and awkward design plaguing early devices. Source: PC NEWS