Difference between the role default and 802.11b/g,802.11b/g/n,802.11b/g/n/ac does these effect internet slowness ,if how to over come it.

[venkanna_siddin]

Hi All,in my ruckus zd portal  i have seen role as default for some users for some users it is not showing any role and for some users it is showing 802.11b/g ,802.11b/g/n and 802.11b/g/n/ac does these specify anything interms of internet effective utilization.
Thanks in advance.