What's the difference between a cerebral vascular accident (stroke) & a transient ischaemic attack (tia)?

Definitive damage. A TIA describes stroke like symptoms that resolve without other intervention within a short timespan, usually less than 1 hour although the classic definition uses 24 hours. A stroke describes irreversible brain tissue damage caused by a lack of blood flow (technically a bleed is also a form of stroke). This damage can be diagnosed definitively on a MRI scan, no such damage can be seen in the tia.
Tia vs stroke. Tia symptoms are transient they disappear after a few hours. A stroke patient has symptoms that are present most of the time permanently. ( or more than 24 hours) a patient with TIA has a propensity for a stroke unless precautions are taken.
Deficits. Tia, or transient ischemic attack, as the name suggests comes and goes away without leaving any neurologic deficit behind it. Cva (cerebral vascular accident) is another name for a stroke. It usually causes deficits (weakness, numbness, speech difficulty) that stay.