The short answer is yes, there are no disability premiums such as SDP & EDP with UC.
You may be eligible for Transitional SDP Element included when your UC award is assessed., but this Element can be eroded over time, meaning when a claimant has certain changes - such as having a new baby or a rent increase - they may not receive any extra UC.
Gary
Nothing on this board constitutes legal advice - always consult a professional about specific problems