Vesta Control Panel - Forum

Okay, so first off, if I replace vsftpd with proftpd, all my users will still work correct?
Also I would like to know are there any major differences between the two?

You can check google: https://www.google.com/#q=vsftpd%20vs%20proftpd

How to you can find here:
http://vestacp.com/docs/#how-to-replace ... hel-centos
http://vestacp.com/docs/#how-to-replace ... ian-ubuntu

Everything should normally work after replacing vsftpd with proftpd.

ProFTPd and VSFTPd are two different software created by two different groups. ProFTPD seems to be more feature rich, and the config file typically resembles that of apache's config file which many find appealing as proftpd also supports certain apache like directives.

VSFTPd seems to make the claim to fame based on its security. Vsftpd is more secure at least in the sense that its by default very restrictive.