sftp-server versus internal-sftp

[Parke]

Hi,

I recently discovered that my ~/.bashrc file was preventing me from
using SFTP successfully.  I then found documentation of sftp-server
and internal-sftp.  However, I could not find answers to the following
questions in the documentation.

1) What are the advantages of sftp-server over internal-sftp?  (I
believe Ubuntu and Debian both default to "Subsystem sftp
/usr/lib/openssh/sftp-server".)

2) What is the advantage of having the subsystem run sftp-server via
the user's shell, instead of just running sftp-server directly?

Thanks!

-Parke