What is the difference between acute ischemic stroke and ischemic stroke?

Acute - Sudden Onset. Acute stroke refers to a stroke that has just occurred. Ischemic stroke may be hyperacute (based on sudden onset neurological symptoms and imaging findings, MRI and perfusion study) and potentially treatable, acute (1-7 d), subacute (7-21 d), and chronic (>21 d).
New onset. An acute ischemic stroke is one whose onset was within the past 24 hours or less. An ischemic stroke refers to brain damage due to an obstructed artery, whereas a hemorrhagic stroke is one in which brain damage occurs as the result of bleeding (hemorrhage).