Less pageviews in top paths than in campaigns

I have a campaign link on a startpage A going to page B. I compare it to Top paths. I look in Top paths for interactions starting on the startpage A and then goes to page B.

The campaign report shows more pageviews on page B than Top paths. I do not understand why there is a difference? Shouldn´t the number of pageviews be the same?

(The numbers of pageviews are small so the maximum number of interactions could not have been met here.)

Grateful for any explaination.

Best regards,