alpaca

Pac is likely misspelled.

Pac has no English definition.

As a noun alpaca

is a sheep-like animal of the Andes, Vicugna pacos, in the camel family, closely related to the llama, guanaco, and vicuña.

As nouns the difference between emu and alpaca

is that emu is a large flightless bird native to Australia, Dromaius novaehollandiae while alpaca is a sheep-like animal of the Andes, Vicugna pacos, in the camel family, closely related to the llama, guanaco, and vicuña.

As an abbreviation emu

is electromagnetic unit.

As an initialism EMU

is with respect to the European Union: Economic and Monetary Union.