Project category vs Ledger posting set up under PMA

Whats the differnce and when it require to set up

Without additional context, take a look at this link. Maybe it can help?

Thanks Jacob

Under the project category, its link with GL account
Path is PMA module-Set up-Categories-project categories

vs

-PMA- Setup- Posting - Project groups - > Select project group, under action pane select Set up drop down - Ledger posting set up

Both the places set up links with Account

Recently noticed that GL account was set up/linked to procurement category but when entry made via item it error out as it will require Account set up under ledger set up,

Trying to understand and have justification BPO / PM

Please let me know any question or require more information

thanks and kind regards