What are the major differences between a migraine and a tia?

Degree: A migraine's main feature is pain whereas a TIA is marked by loss of body function. Both are related to changes to circulation in the brain. Migraine may interfere with your ability to function but to a much more limited extent. Some types of migraine have more features of a TIA and need careful evaluation to determine that they are not symptoms of an impending stroke.

They are different: Migraine is a type of headache whereas TIA is a mini stroke, the symptoms and signs are entirely different. But in migraine you may have what is called hemiplegic migraine where symptoms may resemble a stroke.