Before Smack added native support for Android in Smack 4,1, aSmack was the build environment for using the Smack library on Android, enabling XMPP protocols.
aSmack is a build environment for Smack that uses an existing Smack source to add additional Android specific patches to smack which
- use the built in XML parser provided by the Android library
- add support for DNS SRV lookups
Starting with Version 4.1 smack is able to run without modifications on Android, so aSmack is essentially obsolete.