what is difference between .ssh and .ssh2 directories
There were two major versions of the SSH protocols: Version 1 and Version 2. Generally, the later versions of the software support both versions of the protocol (though I believe it is best practice to disable SSH version 1 support in the SSH daemon/sevice configuration).
The current version of the ssh-keygen program from OpenSSH typically generates keys (for SSH protocol 1 or 2) in a folder named .ssh
Some commercial SSH programs and apparently some earlier versions of openssh might use a .ssh2 folder.