At least one of them is incorrect. The likelihood is they are both incorrect. Liquid tests are generally considered to be more correct than test strips however.
These tests are home test kits, not laboratory testing. All sorts of things can throw off tests, so yes its possible that there is something in your tank that's throwing off your results. The ammo lock is the most likely of the products you have personally added to be an issue. I would trust the liquid test more.
One thing to be aware of. Neither of your ammonia tests actually test for ammonia. Take a look at the test charts. They both test for NH3
(free ammonia) and NH4+ (ammonium) or total ammonia nitrogen (TAN). Its only the free ammonia thats actually harmful.
The proportion of free ammonia to ammonium in the TAN your test is reading is pH and temperature dependant. The higher your pH and water temperature, the more of your TAN is harmful free ammonia. If your pH is on the low side of 7 then its entirely possible your 8ppm TAN isnt harmful. Its still a cause for concern, because its a sign you arent cycled. And a shift in pH could cause a swing in the toxicity of your TAN.
How to get your ammonia down? Cycle the tank. Until you are cycled the only surefire way of getting it down is water changes. Could you give some more details on your tank? Water parameters, tank size and age, filtration, numbers of fish?