The A of the C, A of the T & A of the P had fought very different wars. The chance to exchange ideas & adopt best practices was a unique event. The army Sherman took to Atlanta benefitted greatly from that.
There is a back story... really a back-stab-back-story to the Grant /Thomas/Nashville hoo-ha. Schofield was pulling a Hood, sending critical messages through a back channel to Washington. When Thomas was told about Schofield’s subterfuge, his response was, ‘Why would he do such a thing?’ When the light went on, like Hood, Schofield schemed to get his boss’ job. It is ironic that Grant, who despised backstabbing gossip mongers, would fall victim to Schofield’s insubordination.
If you wonder why Schofield’s messages, which became an open secret, were not included in the official record, look on the title page. He used his editorship to sanitize his chronic curtain climbing & the reaction to it.
On the substantive side, Grant & Thomas were very different generals. Grant was all about tempo, the embodiment of the OODA curve. Thomas was a deep preparation smash-em with one great blow general. They both had great victories, but in very different ways.