Yup, you'll see this if you've worked with datacenters too, you can get a 100mbit connection on a gigabit link on which you mostly get gigabit connectivity, but

Yup, you'll see this if you've worked with datacenters too, you can get a 100mbit connection on a gigabit link on which you mostly get gigabit connectivity, but only 100mbit of it is guaranteed for much, much cheaper than you can get a guaranteed gigabit link. And in my experience (for personal and small business purposes at least) that guarantee is rarely worth its name.