Why do Syscoin addresses in exchanges start with 'S' while in the blockexplore when searching using the txnId, addresses start with '1'?
polo, bittrex and maybe others relied on using S style syscoin 1 addresses on their exchanges but in Sys 2 we used new address scheme that allows sys keys and btc keys to coexist on the same private key. Syscoin 2.0 and 2.1 are backwards compatible with S style, the address prefixes are the only difference but the private keys are the same for bother S/1 style addresses, you can run validateaddress on the addresses to confirm. Since they create new S style addresses to deposit when you send it will show as 1 style address because that what sys 2/2.1 blockchain uses by default... inside the private key is the same and the exchange will receive coins on S style address that matches the private key of the 1 style address, the destination is the same.
The design decision to switch to 1 style allowed us to innovate features such as DirectBTC/DirectZEC features.