Cof A's
Not a lot of difference these days.
The major differences are these;
Private Catergory; You may do your own 50hr/Annual inspections and basic maintenance. You may sign the 50hr in the log book but a licensed engineer must sign for the Annual. The Star Annual must be signed by an approved organisation. The maintenance that you are allowed to do is limited to such things as changing the oil and tyres etc. The full list is contained within the LAMS schedule.
Public catergory; All scheduled inspections/maintenance must be undertaken by a licenced engineer.
The saving in cost (Private Cof A) if any will depend how much work you do yourself.
The catergories are changing to Utility & Public Catergory. The Private Catergory is going as each Star is completed. Utility aircraft will be usable for Hire & Reward and for Arial Work. However for the later to happen the last checks will need to have been completed by a licenced engineer.
Insurance is a matter for you. If the aircraft is insured only for your own use then it is only then that the insurer will pay. If you wish to insure for all users then that is the insurance that you need to pay. The insurer in the main is only concerned that the aircraft is used legally. Some insurers apply restriction to the use and also for types of user.