I know only three differneces.
1) ADO wroks on Connected architecture, while ADO.Net on DisConnected Architecture.
2)ADO is used to create Client Side Cursors while ADo.net create both client as well as server.
3)In ADO,data is converted before transmitted whike in ADO.Net no transformation takes place.

IF FRNDS U KNOW DIFFERENCES OTHER THAN THESE PLZ DO REPLY.