That is only telling you your LAN speed. It appears that the new modem will output at Gigabit speed and the older one was the standard 100 Mb/s speed. Do an actual speed test at the Comcast site. I'll guarantee you won't be getting 100 Mb/s or Gigabit speed from them.
a new cable modem for my Comcast broadband high speed internet.I was fine with the one that they supplied and got 100Mbps with the connection and I thought that was real fast. I just got tired of paying $7.00 a month rental for the modem. (which was a Thompson model DCM425). The one I purchased is a Motorola SURFboard eXtreme and I get 1Gbps internet speed now . I can't tell any difference though, where would alla this extra speed make a difference?...........Digger