I don't think these are two completely different entities as ACH's are considered EFT's.

I am just confused on where one stops and the other begins. I know that Reg E regulates EFT's and NACHA for ACH's but which type of payments and transactions fall under Reg E and NACHA respectively?

NACHA covers payments that flow through the ACH system. Of those, the ones posting to consumer accounts are also subject to Regulation E.

Regulation E covers consumer account transactions that flow via the ACH system, plus other EFTs such as ATM and debit card transactions, transfers initiated one at a time by telephone or web site, many bill payment system transactions. It does not cover transfers made by Fedline, CHIPS, or similar systems designed for bank-to-bank and business transactions.

Does NACHA trump Reg E on the transactions that post to consumer accounts? How do you know which to follow if a dispute arises? Or don't the two conflict? Thanks John.

Regulation E never gets "trumped." It can get augmented. For example, Regulation E only provides a right of stop payment on preauthorized debits (recurring). NACHA rules provide a stop payment right on all debits.

As far as you consumer customer is concerned, you must follow Regulation E, and layer on NACHA rules when they are more protective of the consumer. But a good example of where NACHA rules can protect the bank less than Reg. E protects the customer is the matter of returning unauthorized EFTs. Reg. E gives the customer the right to recover funds for any unauthorized EFT unless its one of a series of related EFTs and occurred more than 60 days after the day the statement reflecting the first of the series is made available to the consumer. NACHA allows the ACH to be used to return an unauthorized EFT only within 60 days of its Settlement Date. That can leave a gap of up to 30 days in which the consumer is protected by Reg. E but the bank cannot return the item using the ACH network.

In such cases, the bank would have to pursue a refund under the Originator's and ODFI's warranty on the item, but outside the ACH framework.