Was originally told i had a dissection of my internal carotid artery.... now being told it is a pseudo aneurism..... what exactly is the difference?

See below: An pseudoaneurysm is when there is a breach in the blood vessel (usually due to injury), but the bleeding gets trapped by the surrounding tissue forming a hematoma. A dissection is actual tearing of the layers of the carotid artery - in this case. In general terms, dissection tends to be more of a surgical issue. In both cases, treatment depends on the size, etiology of the condition.