He's talking about the difference between the wires being inside thinwall conduit called "pipe" in the trade. It will be a hollow, metal tube and it will have stranded wires inside without a sheath or outer cable. Romex is the generic term given to electrical cable that it used indoors instead of putting everything into pipe or conduit. It will have a heavier, usually white, sometimes yellow, outer layer that is easily stripped away. Inside there will be three wires, a black, a white (neutral) and the bare ground wire which does not have insulation on it. The three inside are SOLID, not stranded. The three wires will have a paper layer wrapped around them that's underneath the outer layer. Hope this explains the difference. If you google Romex, I'm sure you'll get a pix of it. Otherwise, just look in your basement where the wires are run and you'll see it. Depending upon how old you are and how long you have been in the business, you might see the romex outer shield be white, yellow, black, brown, muddy lookin' non-descript ****, or even (God forbid) fabric that looks like a wide-weave canvas. Now, the romex that is white is usually 15 amp, 14 gauge, while the yellow, USUALLy is 12 gauge, 15 amp. But always look at the writing on the cable itself to determine the gauge and amperage. I've pulled in miles and miles and miles of the white stuff that was all 12 gauge.
Cheers,
Jim