What kind of ethernet cable do major companies use?

Major companies do not use a special type of ethernet cable that improves internet connection speed. They simply order special internet plans that are typically only available to medium/large businesses as they are very expensive. For example, your company could have a T1 internet connection, much faster than consumer internet speeds but also much more expensive. There are different categories of ethernet cable but these do not normally improve internet speeds at all. As far as I'm aware, there are no special types of ethernet cables exclusively available to big companies.