What is the difference between "у тебя всё хорошо?" and "ты в порядке?"?
The difference is that the latter expression is not Russian in origin and actually comes from amateur translations; it literally renders the English 'Are you alright/OK?' Typical Russian expression of that sense is: У тебя всё в порядке (хорошо)? The version Ты в порядке? while often used (definitely not by everybody) in the recent years, doesn't sound too sophisticated to me. If you google that expression in books, unlikely you'll find it in classical literature (most results come from books written in 2017-2019).