Question about end tables

I have a dumb question about end tables. My DH and I are debating on this as we buy two for our living room (one on either side of our large sofa).

Do they need to be the same height or lower than the couch they are next to? Or can they be higher?
TIA!

Re: Question about end tables

I don't like them when they are higher. Then, your arm winds up banging into it when you use the arm of the chair. Plus, it's more awkward putting things like cups on the table. I like them to be no higher than the height of the chair arm when it's compressed under the weight of someone's arm.