[vchkpw] Qmail maillog vchkpw-submission vs vchkpw-smtp

[LHTek]

In the /var/log/maillog file what is the difference between these 2 entries 
(vchkpw-submission, vchkpw-smtp)?

example:
Mar  4 17:27:03 michael vpopmail[14701]: vchkpw-submission: (PLAIN) login 
success t...@domain.com:64.185.3.238

Mar  4 10:54:42 michael vpopmail[29027]: vchkpw-smtp: (PLAIN) login success 
t...@domain.com:64.57.239.114

!DSPAM:5316b90234262261610445!