6740T-1G
6740T
They are both the same, but the 1G is limited using a license.
They are both copper RJ-45 ports
6740
This is an SFP+ switch
Pricelist
the idea is simple.
You can get the same switch with less ports
then upgrade later on using licenses.
So a 24 port switch is a 48 port switch.
the 64 port switch simply means you have enabled the QSFP+ 40 G ports too.