Users can differentiate their MT5 account(s) and MT4 account(s) based on the permutation of their account number.
The MT4 account number follows the following permutations:
MT4 Live 1 Server: 137xxxxx(7 Digits)
MT4 Live 2 Server: 40xxxx (6 Digits)
The MT5 account number follows the following permutations:
MT5 Live Server: 523xxxxx (7 Digits)
Hence, if an account number starts with 5 and has 7 digits, the account is a MT5 account number