From the descriptions these seem similar:
corex alias_subdomains (http://kamailio.org/docs/modules/devel/modules/corex.html#idp18017160):
Register a domain and all its sub-domains to match the “myself”
condition. It can be set many times. Its full format is:
'proto:domain:port', allowing to set restrictions on protocol
and port as well. Protocol and port are optional.
alias core parameter (http://www.kamailio.org/wiki/cookbooks/devel/core#alias):
Parameter to set alias hostnames for the server. It can be set many
times, each value being added in a list to match the hostname when
'myself' is checked.
Is the only difference that corex alias_subdomains can include 'proto' ?