There are many different types of Certified Public Accountancy firms out there. Some specialize in financial statement preparation. Others in consulting and yet other like ours is a tax preparation firm.
When a firm specializes in tax preparation the firm will usually be well versed in IRS procedure and very tuned into filing deadlines and changes in tax laws.
A tax preparation firm will usually know local laws better when it is local or regional and will have access to other tax preparation firms to collaborate with.
As a general rule a firm that specializes in tax will provide you with a higher degree of expertise than a general practice firm or an audit firm.