Account Transcripts are a line by line summary of every action on a tax year by the IRS. It will show any balances due (including penalties and interest), when a return was filed, all payments or credits, all penalties and interest assessed, and the dates of any time sensitive correspondence issued or your resolution status.
Wage & Income Transcripts show information about all the income documents received by the IRS for that year- a great way to make sure you're including everything they expect to see for a particular year. They will also show any Federal withholding, but NO STATE INFORMATION, so if you had state withholding but can no longer accsss copies of the documents, you might miss out on getting credit for withholding for any state or local taxes,