I am coding a Windows server application that uses Electrum wallet for a Website. So each user get a receiving address to deposit and all the deposits to receiving addresses are collected to one balance at the end. And when user do a withdrawal, then the server sends the request to electrum. I want to know what is different between using electrum and hosting a full node (that requires bandwith and a lot of stroage)?

More problems with paper wallets, is that if we want to transfer user funds to the main wallet, We'll pay a lot of fees to move each funds from each wallet to the main wallet.