A filament light bulb is just another name commonly used for the vintage Edison light bulbs. Those reproduction bulbs are made to look like the original Edison bulb created over 100 years ago. The word Filament itself refers to the wire or thread inside the bulb which lights up when you turn it on.
These are some of the names manufacturers and consumers use to call those bulbs; Filament bulbs, Edison Bulbs, Antique Bulbs, Vintage Bulbs, Nostalgic Bulbs, Original Bulbs, Squirrel Cage Bulbs, old-fashioned bulbs, and retro bulbs. All those names basically mean the same thing!
There are also different shapes, sizes, and filament designs those bulbs come in.