The answer depends on what you want tell it apart from!
How do you tell goldfish apart there genes
You can tell substances apart by looking at their properties
You can tell rocks apart by its hardness, cleavage, and streak
it depends what you are telling apart
Meerkats tell each other apart with smell and dominant
Depends what "them" is
there are seven types;Snapping Turtlessea turtlespond turtlesmud/musk turtlestortoisessoft shell turtlesthe leather back turtle
It depends what type of turtle. Some tertles can hurt incredibly bad, when others are near harmless.
For the average human viewer there appears to be little way to tell a Pill Bug apart but they do have markings on there backs which can allow them to be told apart.
As humans we have a hard time telling penguins apart. However, They can tell each other apart by distinct vocalizations.
You can tell it apart by Eating the burger and licking the rockdifferent taste s LIKEa BOSS