FAQ : Nexgard Versus Nexgard Spectra - What is the difference
NEXGARD contains the active ingredient afoxolaner which has been proven to kill both fleas and ticks and to protect your dog for a whole month.
See NEXGARD product label for full claim details and usage instructions.
Like NEXGARD, NEXGARD SPECTRA contains afoxolaner, providing the same excellent level of protection against fleas and ticks. Additionally, NEXGARD SPECTRA contains the active ingredient milbemycin oxime, which provides protection against heartworm and intestinal worms, making it the most complete protection against fleas, ticks, heartworm and intestinal worms in just one tasty chew.
See NEXGARD SPECTRA product label for full claim details and usage instructions.
Source: http://www.nexgardspectra.com.au/faq