Usually used interchangeably by doctors, but correctly speaking, all symptoms have completely resolved within 24 hours in a TIA, whereas in a stroke (of any severity) symptoms persist for more than 24 hours.
It is common to say "mini stroke" if the symptoms are not very bad. However, be wary. The diagnosis of any short-lived or mild neurological symptoms is difficult, and many events may be migraine related.
Even immediate MRI scanning cannot always help with diagnosis in this situation.