Just like any kind of bite, bed bug bites are hard to really say for sure what they are. Some characteristics to look for would be a symmetrical line of bites as the bed bugs like to line up to feed. Some folks want to know if they have bed bug bites or flea bites. You can eliminate the possibility of fleas by a process of elimination. Are there dogs or cats present? Are the bites only on the legs. Do you see the fleas? Are you only getting bitten at night? Fleas will bite any time of day, and they are easy to detect because you usually feel the fleas biting you. I would recommend asking a doctor if you are not certain and also arrange for a pest controller to inspect the property.