I was reading about OpenSSH and I have the following questions:

1. What is the difference between ssh and slogin?

2. What is the difference between scp and sftp?

3. Does sshd (on server side) provide separate server processes to handle each client (ssh, slogin, sftp, scp) type requests or just one process for all client types?

4. is the secure shell a standalone shell like bash etc., or just a process that encrypt/decrypts traffic and communicate to ordinary bash process locally?