A CPA stands for Certified Public Accountant. This is someone who has passed the board exam and is a certified accountant. The accountant is someone who has graduated from the 4-year course but has not taken the certification or has not passed the certification yet. The main difference between the two is that CPAs can create audited financial statements, but accountants will not be allowed to do this because they do not have the certification to prove that they will be able to handle documents like this.
Businesses can hire an accountant for their simple accounting needs, but companies would need CPAs, especially if they would need someone to represent them when the IRS is summoning them.