ftp vs sftp

I am running below. It uses sftp protocol and it is getting connected.
winscp.com /console /log /command "option batch abort" "option confirm off" "open uid1:pwd1@xxx.xx.xx.xxx"

But, when I run below (other server), It uses ftp protocol and it is NOT getting connected.
winscp.com /console /log /command "option batch abort" "option confirm off" "open uid2:pwd2@yyy.yy.yy.yyy"

Is something need to be specified , if it is ftp protocol in the above command?

WinSCP defaults to SFTP. Although you could have changed the default, it still should not use different protocol for different servers. The only explanation would be that you have a stored session with name "uid2:pwd2@yyy.yy.yy.yyy" that have FTP protocol set. But I doubt that. Log file could give more clues (/log=log.log)

Anyway, to learn how to specify protocol see documentation:
https://winscp.net/eng/docs/scriptcommand_open
https://winscp.net/eng/docs/session_url