The second thing you will notice is the dark yellowish/orange yokes. You will also notice the yokes are firmer. Chickens will lay beautiful firm dark yoke eggs if you let them graze in fresh new pasture, eating bugs, grass, and taking in lots of fresh air. Bugs are a huge part of the diet of a chicken. Chickens need large amounts of protein because they are omnivores just like humans.
The healthiest eggs to buy are true free-range, pasture raised, soy free, chicken eggs.