What is the difference is between low-density vs. high density in relationship to switches?

I am trying to figure out what the difference is between low-density vs. high density in relationship to switches. Thanks. The computer science definition of "density" is the number of units of useful information contained within a linear dimension (Websters.com). Basically, the prior generations switches could push out 100 mbps in larger bulkier boxes. Today's generation has gotten smaller and can push out gigabyte speeds or even 10 gigabyte speeds. However, as technology changes so will the use of term high density. There is no true definition. I view it as a description of the current technologies at that particular point in time.