What is inline validation?
In short, inline validation is an effort on behalf of the form to help users correct information as they go, ideally so that when the point comes to submit the form, they are more likely to submit it on the first attempt. The more failed attempts a user makes to submit the form, the more likely they are to give up.
What is UX validation?
What is UX validation? In a broad sense, UX validation is the process of collecting evidence and learning around some idea with the aim of conducting experiments and user testing to make informed decisions about product design.