I could see earlier my colleagues have already shared you the datasheet for X summit series switches.
Please find below the link for A/B and C series datasheet link to find more information on them:
Else
You can always go back to our extremenetworks.com site then select the product section under which switching there you will get all the datasheet for the selected product to find the difference.
If you are looking for data's in a tabular column format. Comparison of A4 vs X440G2 & B/C vs X450G2. You could contact our local Sales Team in your region, they could help you with this request.