Laptops today support both the bandwidths. And often get faster speeds since they have the ability to connect to the 5Ghz bandwidth.
Unfortunately the older laptops are not lucky enough. They can only connect to the 2.4Ghz bandwidth which obviously offers slower speeds than the 5Ghz bandwidth.
But as always for every problem there is a solution. And in this case in order for the older laptops to connect to a faster bandwidth one must buy a WiFi adapter.
The adapters are quite easy to setup. It has to be plugged into the USB port of your laptop. And because of this even an old laptop would not be left behind and would be capable of achieving high speeds.