The name of a given plugin is defined in the data structures inside the plugin. The filename is the name of the file that contains the plugin. The two are similar, but they are not the same. For example, the name of the Cassandra storage engine plugin is CASSANDRA and the filename is ha_cassandra.so. The name is case insensitive, so when referring to it we can use CASSANDRA, Cassandra, cassandra, or even CaSsAnDrA if we want. The filename, on the other hand, is case sensitive if our underlying filesystem is case sensitive.

The INSTALL SONAME command is just a variation of the INSTALL PLUGIN command. The main difference is that INSTALL PLUGIN requires two sets of information, the name and the filename, and INSTALL SONAME just needs the filename. The filename must be quoted. Here is the recipe using INSTALL PLUGIN:

INSTALL PLUGIN Cassandra SONAME 'ha_cassandra';

Apart from being shorter, INSTALL SONAME is no different from INSTALL PLUGIN, functionality-wise.