會計師樓同唔同會計師事務所.?

They are the same. 會計師事務所 is commonly used today while the 會計師樓 is an 'traditional' name.
These firms have practising accountants CPA(Practising)( Accountants holding a practising certificate issued by HKICPA ) as a sole proprietor or being a partner. Professional accountant without a practising certificate could only call themselves CPA and NOT CPA ( Practising ). Only CPA ( Practising ) could carry out a statutory audit of a limited company and sign the Auditor's Report as required under the Companies Ordinance
But, there are some accounting companies in the market calling 會計事務所 without the wording 師 means these are ordinary business firms established by any person with no practising accountant and hence no statutory audit could be carried out.