These products are not comparable. All pets need 3 types of parasite prevention: heartworm, intestinal parasites, and fleas. Most pets need some tick prevention as well. Trifexis prevents heartworms, intestinal parasites, and fleas. If you have no ticks in your area, you might be able to get away with Trifexis alone. On the other hand, Frontline protects against fleas and ticks. You ALWAYS need another product in conjunction with Frontline, because you are not getting any protection against heartworms or intestinal parasites.