Let's say you have two sentences you are studying: "John ran to the mall for Pocky." and "I'm running Minecraft on the server."
A flashcard app tracks how often you get each one right or wrong. And its very possible to see both cards in a single session.
Parsnip tracks words though. "Ran" and "running" are both forms of "run" so you reviewed "server" recently Parsnip knows you also reviewed "running" at the same time.
Parsnip works at the word level. It breaks the content into words and provides relevant information such as the dictionary form of a word, part of speech and readings/pronunciations.
Google translate works everything at once. It is possible words from the original text don't show up in the translation at all. Like when a completely different phrase is used to convey the same meaning in the other language.
Not knowing about these cases can make using google translate frustrating at best.