Total finance n00b question - What's the difference between using the Transfer Fund functionality, and using a JE? Why not just do a simple JE, debit one bank account and credit the other ?

No real difference. The transfer funds entry is just a fancy wrapper on a JE. Could be useful for reporting to use a transfer funds entry so you can more easily distinguish it from JEs.

Thanks dude @RJMNS

But if you have multiple currencies you cant just do one journal to do the transfer

Ah interesting good to know @Lisa Reed. I do see that one of the limitations is that at least one of the accounts in this transaction needs to be denominated in the sub's base currency. Along with the one I knew about where you can't do interco bank transfers. Could still definitely see some use cases for this though.

The annoying thing is you cant script bank transfers... If you have multiple currencies, you basically have to do two journals - and use a clearing account to flush out the exchange

Also- JE's tend to break bank recs, and better control over transactions if you make people enter bank transfers as opposed to just opening up JEs