User interface or Ui
The interface of a website, or anything that allows us to make a better connection with a product, is called UI. For example, if we want to open a door, we use its handle and without it, the door will be unusable. In the case of the digital world, any possibility that makes it easier for users to use the site is called UI.
User experience or Ux
The experience of users of your site and the good or bad feeling they get from it is called UX. In UX, the appearance of the site is not a priority, but this function is what makes your site stay in the minds of the audience or not, in other words, user experience or UX means looking at the use of the product from the sight of the customers, i mean you should put yourself in their shoes to understand them better; so it can be said that UX has a direct effect on the SEO of the site.