Yes, it seems I underestimated the difference: "In spoken Cantonese the frequency of use of Cantonese dialect words is close to 50 percent (Li, et. al., 1995, p236)." (from https://www.aclweb.org/anthology/P98-2238.pdf).

They're still a lot closer than English and Spanish or even French and Spanish (https://www.ezglot.com/most-similar-languages.php).