Not the same thing at all. The £164 is payable to the state - though it appears to include some 'helpline' type advice (if you need it) on getting the form right.
The closest equivalent fee in Ireland is the €60 payable to the courts service to register an enduring Power of Attorney (with no helpline).
You have the option to do without legal advice in the UK (you can use a "Certificate Provider" who does not necessarily need a formal qualification). However, many people in UK will still see a solicitor and avail of legal advice. When this happens, the costs are much the same (maybe even a little higher) in the UK.