Where the coins sit is the whole distinction
An exchange with built-in bots needs your funds to be on that exchange. That is not a criticism: it is what makes those bots possible in the first place, and it buys you real things, including one company answering for both the exchange and the automation.
The trade-off is that choosing an exchange and choosing a bot become one decision. Vectixs keeps them apart. Your coins stay in the account you already picked for its liquidity, its listings, its fee tier and its regulatory standing, and the automation is a separate thing you can stop using without moving anything.