506-T is used to get transcripts of the Return Transcript and Wage and Income Transcript, while 4506-T-EZ is used to get transcripts of just the Return Transcript, Income Verification Express Service, and Record of Account.

Form 4506, titled "Request for Copy of Tax Return," is a document filed by taxpayers in order to request exact copies of previously filed tax returns and tax information. Taxpayers can use Form 4506 to request returns from up to six previous years. Different types of returns available under a Form 4506 request include the 1040, 1040A, 1040EZ, 1120, 1120S, and 1065 (amongst others).

Currently, it costs $43 for taxpayers to get a copy of their filed return, though this fee is subject to change over time. It is important to note that a Form 4506 request applies only to paper copies of tax returns, and is not available for copies of returns filed electronically.

When an exact copy of a tax return is not needed, taxpayers often use two alternative forms in order to request free transcripts of previously filed tax returns: Form 4506-T and Form 4506-T-EZ. Form 4506-T is used to get transcripts of the "Return Transcript" and "Wage and Income Transcript," while Form 4506-T-EZ is used to get transcripts of the "Return Transcript," "Income Verification Express Service," and "Record of Account."

Though Form 4506 is often used to obtain copies of tax returns, it is important to note that it can also be used to change a previously filed return. To request a change to a previously filed return, taxpayers must use Form 4506-T, check box 3, and enter an explanation of the change they are requesting.

In sum, Form 4506 is a form used by taxpayers to request exact copies of previously filed tax returns and other tax information. Depending on the information requested, Form 4506 can cost $43, though taxpayers can alternatively file Forms 4506-T or 4506-T-EZ to get free transcripts of a previously filed tax return. Additionally, Form 4506-T can be used to request changes to filed taxes, as long as an explanation for the change is included.