Actually, there are those paid SSLs that would come with a dedicated IP for your website instead. The free ones - you don't get that dedicated IP, but you still have the SSL/HTTPS indication for your website.
I don't notice any differences, but the paid SSL, when you purchase that from a hosting provider, they will assign a dedicated IP to your hosting plan, and through that dedicated IP, the HTTS/SSL is provided accordingly.
So if it's SEO point of view, if you were to use a shared hosting plan, using a paid SSL that comes with the dedicated IP, that would somehow segregate your site from potential other spam websites that could be in your neighborhood.