ACH and wire transfers are both ways to send money to other people or institutions. Wire transfers are usually faster but cost more than ACH transfers.
EFTA notably defines an "electronic fund transfer" as "any transfer of funds ... which would increase the administrative expense for these types of transactions and could impede the ordinary ...
An ACH transfer ... transfers are electronic money transfers sent from one bank to another across an Automated Clearing House (ACH) Network—a digital hub that transfers funds.