Ischaemic strokes are caused by arterial occlusion (e.g. by an embolus or a ruptured plaque which thromboses up).
Haemorrhagic strokes are caused by ruptured vessels. Leaking blood can compress and injure surrounding tissues, and can also cause a lack of blood to its usual supply areas downstream.
To answer your question then, ischaemic strokes in Western societies account for about 80% of all strokes, with haemorrhagic strokes making up the remainder.
This distinction is important, since if patients with ischaemic strokes can get intravenous thrombolysis within three hours (e.g. with the 'clot-buster' called recombinant tissue plasminogen activator), they tend to have a better outcome, provided there are no contraindications to this treatment. On the other hand, giving thrombolytic therapy to a patient with a haemorrhagic stroke could obviously kill them!
Although there are a few clinical guides to distinguishing which type of stroke the patient is having, they are unreliable, and the patient will need either a CT scan or an MRI to tell which type of stroke it is.