FTP over TLS

Explicit vs Implicit FTPS

FTPS (SSL/TLS) is served up in two incompatible modes. If using explicit FTPS, the client connects to the normal FTP port and explicitly switches into secure (SSL/TLS) mode with "AUTH TLS", whereas implicit FTPS is an older style service that assumes SSL/TLS mode right from the start of the connection (and normally listens on TCP port 990, rather than 21). In a FileZilla client this means prefixing the host with "FTPES://" to connect an "explicit" FTPS server, or "FTPS://" for the legacy "implicit" server (for which you will likely also need to set the port to 990).

SSL/TLS (FTPS) vs SSH (SFTP)

FTPS (FTP encrypted with SSL/TLS) should not be confused with SFTP (SSH). The latter is a completely different protocol, with more information here.