Can you Explain what is Link wheel?

Link Wheel is a network of websites (e.g. Squidoo, Hubpages, Wordpress, blogger, etc.) and blogs connecting with each other, which links them to your website. Unique content must be added on your link wheel. This could include articles that are focused on one unique keyword to rank on the Search Engine Result Pages. However, inappropriate building link wheels can harm your website.

isnt link wheel the same as link farm