A plotter is a specialized printer used for drafting and generally uses big (usu. 3-4ft length) rolls of paper. Some types do use pens, though they're usually short and specially shaped making them difficult to use manually
The OC was referring to the pens that work like an auto-feeding hot glue gun using colorized glue, or PLA if the heating element gets hot enough.
Not all printers are, but FDM printers are.
SLA printers, the one uses projector and resin to makr high detailed figurines or parts with precision are basically fancy nail polish and curing light combimed.
Yup, this is how I explain FDM printing to friends. It's like a giant hot glue gun, layer one layer at a time. Except instead of a giant hole for glue, it's a 0.4mm hole, really tiny.
Calculators calculate while computers can be programmed with new instructions. Fancy calculators that can be programmed though, as you say, are basic computers. Meanwhile calculators that run BASIC are BASIC computers.