I just came across the words from the site "https://www.androidpolice.com/gmail-mark-all-messages-read/", which indicate, as for me the same thing but by using different words in the article "volume bar", "volume slider" and "volume rocker". So, my question is do these three indicate the same thing as the volume adjustment function on mobile phones? I've included a screenshot for your reference. Thanks
"volume bar", it the graphic itself. A bar, in the context, is a shape.
"volume slider" refers to the graphic if and only if it can be used on a touchscreen to alter the volume. "Slider" indicates the possibility of sliding the graphic to that effect.
"volume rocker" is the physical exterior part - a button on a central pivot such that it rocks - usually on the edge of the phone, that can be pressed up and down.