I think your Xfinity Tech was referring to their Fiber Network that reaches your curb.  Xfinity residential customers have cable Internet (coaxial cable connection in the home).  Unless they’re offering in some area.  

If you have coaxial connection in your home, you have cable Internet.  

Fiber goes into the apartment, and the box that Xfinity installed on the wall won't allow any equipment except X-Fi equipment for fiber only. Xfinity stated it's only that way for 1-5% of residential customers; yet, if shopping at Arris I didn't recall any indication that I needed fiber, because all indications were that Xfinity only uses cable. In response Xfinity noted that fiber is new yet admits that the fiber at my building was installed three years ago. Xfinity agrees that they use coaxial connection at residential addresses. What are 1-5% of people to do if they purchase a surfboard when information is given to only 95% of customers? As you see, Arris responds to my question in correctly by stating that goes to the curb.