Google's John Mueller said the other day on Twitter that Google "definitely" scores or has different calculations and formulas for internal vs external links and signals.
To be fair to John, which I am not always (not intentionally), John only answered this tweet with one word - the word "definitely."
Here is the tweet in context:
definitely.
— John ☆.o(≧▽≦)o.☆ (@JohnMu) August 16, 2017
Question was "are there any differences between internal or external score/juice/strong calculation formula/s?" John answered "definitely."
Of course, most SEOs already felt that Google has different signals for internal links versus external links. I.e. if you get a link from a third party site versus linking to your own content within your own site - that is weighed differently.
It does make logical sense. But yes, internal links are indeed still powerful for many reasons.
Forum discussion at Twitter.
