Generally speaking there is no major difference between left and right contact lens. The only difference that makes you pay some attention towards the contact lenses of both eyes is the “Prescription”. At the same time; if the prescription for both the eye is same then you can wear left lens in the right and vice versa at your first wear ONLY.
Contact lenses in plano when are packed in the vials or blisters; have no differences. However it is advised to put your contact lenses in respective wells as soon as you take them out from their packaging. Though there are no major differences; it is suggested to still pay attention on your contact lenses after wearing that which is which.
Actually contact lenses adapt to the base curves of your eyes. Obviously the base curves should be the same for both of your eyes; but side dominant sciences approves that there are minor differences in human body parts i.e.one side of the body is slightly heavier than the other side of the body. This is why when you begin wearing contact lenses; you should not have both the caps off your contact lens case together.
To keep the issue less-complex there is one simple tip. Always deal with the right contact lens first. Wear it first and also remove it first. Prescription contact lenses have less chances of being mixed with each other; because even if they do you might be able to tell the difference upon wearing (in case of different prescription for both eyes). However; for plano contact lenses it becomes difficult to tell the difference.
Always deal with right contact lens first and you will save yourself from many tensions!