Meth and amphetamine are very different drugs, but a bootlicker wouldn't know the difference. She could also have been spiked and left to die by the cop, can't really know without a proper investigation, which the police never subject themselves to.
They are different drugs in the sense that methamphetamine will cause more serotonin release and will act longer than amphetamine, but they will both cause increase in blood pressure, increase heart rate and increase internal temperature. The rest of your comment is right though.
Her source of trust was instagram. The cop’s instagram led her to travel to Arizona and be with him. She was convinced by his instagram that she agreed to do all of this. That’s really dumb and it’s what you get playing stupid games with strangers on the internet.