user-1: My question is in relation to the operational difference between a merkle root and a plain old message digest.
To calculate a merkle root I need to complete the following steps :

hash each transaction in a block
create a merkle tree from all the hashed transactions
work back up the merkle tree hashing pairs of transactions until I calculate the merkle root

To create a plain old message digest I would do the following :

Take all transactions in a block hash them at the same time to create a message digest

My question is, how is a merkle root more beneficial from an operational standpoint than a plain old message digest?

user75001: Initially, they appear the same, only considering that there is a hash included in the block.
A Merkle Tree is more efficient to prove a transaction is included in a block since otherwise, it is necessary to have and hash each transaction to prove a transaction is included using a message digest, so a full node can do this, but an SPV client (and a pruned node looking outside the blocks it has kept) cannot.
There is some more information on how this works in these answers: Merkle Root and Merkle Proofs

-1: <p>My question is in relation to the operational difference between a <strong>merkle root</strong> and a plain old <strong>message digest</strong>.</p>

<p>To calculate a <strong>merkle root</strong> I need to complete the following steps :</p>

<ul>
<li>hash each transaction in a block</li>
<li>create a merkle tree from all the hashed transactions</li>
<li>work back up the merkle tree hashing pairs of transactions until I calculate the merkle root</li>
</ul>

<p>To create a plain old <strong>message digest</strong> I would do the following :</p>

<ul>
<li>Take all transactions in a block hash them at the same time to create a message digest</li>
</ul>

<p>My question is, how is a merkle root more beneficial from an operational standpoint than a plain old message digest?</p>
 75001: <p>Initially, they appear the same, only considering that there is a hash included in the block.</p>

<p>A Merkle Tree is more efficient to prove a transaction is included in a block since otherwise, it is necessary to have and hash each transaction to prove a transaction is included using a message digest, so a full node can do this, but an SPV client (and a pruned node looking outside the blocks it has kept) cannot.</p>

<p>There is some more information on how this works in these answers: <a href="https://bitcoin.stackexchange.com/questions/69018/merkle-root-and-merkle-proofs">Merkle Root and Merkle Proofs</a></p>
