What’s the difference between "Help Center" and "Knowledge Base" sections on a website, if there’s any?

Which is better to use for a page with articles (explaining how to use the app)? Because I've seen different companies use either of the mentioned. I even saw some use "Help & Knowledgebase"? Which should I choose?

p.s. I want to put this name (HD or KB on the landing page and add an anchor link leading to it).