Differential diagnosis by conventional radiography (CR) is really difficult. Some tips on CR may be buccolingual expansion (since the expansion of keratocystic odontogenic tumours is usually smaller than that of ameloblastomas) and root resorption of the adjacent teeth (that  is more common in solid/multicystic ameloblastomas while it is rare in keratocystic odontogenic tumours). There is an "old" article (1972) in Radiology "Differential Radiographic Diagnosis of Lesions of the Jawbones " by Eversole LR and Rovin S. that differentiate the different patterns on CR of the lesions of the Jawbones.

However, it remains still difficult the differentiation on CR and, for this reason, CT may help in their differentiation.  On CT keratocystic odontogenic tumours usually show lower CT density than ameloblastomas due to their different content; moreover CT density in keratocystic odontogenic tumours is usually more heterogeneous than in ameloblastomas and the presence of an high density areas within the lesion is highly suggestive of keratocystic odontogenic tumour. Finally, both on CR and CT, keratocystic odontogenic tumours are more frequently solitary unilocular lesions (ameloblastomas can be unilocular but in 80% are multiloculated expansile "soap-bubble" lesions).

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Totally agree with Dr. Federica. Conventional radiography is difficult to differentiate between the two leaions. Except that, ameloblastoma mostly appear as multilocular radiolucency in compared with OK which is usually appear unilocular either in dentigerous relationship or in place of missing undeveloped tooth or lateral to tooth surface.

Thank for all, of course , the presence of high density area and degree of bone expansion ( using of CT) could help an examiner to differentiate plus clinical and histology test .

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I agree with the above comments, but in addition I would like to add that we need to look for bucco-lingual expansion which is reported significantly more in ameloblastoma. In OKC, there is more of a medullary spread and the cyst grows anteroposteriorly within the jaws rather than bucoolingually. 

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I concur with everyone's contribution and I hereby commend your effort.

Permit me, to take us back to the question, and summarize the answer. ... " Are there diagnostic radiological features that help to differentiate between KCOT and ameloblastoma? Answer, : There are radiological features that are suggestive of differences between the two and may help to differentiate between KCOT and Ameloblastoma but these are not diagnostic.