Now a day you will find top web hosting companies having more or less consistent features like Disk space, Bandwidth, Control Panel,
Email account, Scripting language and the ability to direct customer support either through phone, email or live chat option.
Among them bandwidth really matters. Because bandwidth is the amount of traffic that is allowed to occur between your web site and the rest of the internet.The amount of bandwidth a hosting company can provide is determined by their network connections, both internal to their data center and external to the public internet.

A very simple analogy I have seen in a blog that think bandwidth and traffic as highways and cars. Bandwidth is the number of lanes on the highway and traffic is the number of cars on the highway. If you are the only car on a highway, you can travel very quickly. If you are stuck in the middle of rush hour, you may travel very slowly since all of the lanes are being used up.