Difference chemical pregnancy / early miscarriage

How can one tell the difference between a chemical pregnancy and an early miscarriage? I only took one test, vfl showed up. One week later, I had a huge migrain outbreak and started bleeding. I only had mild cramping and it was like having my period, only I am never late. Started bleeding at almost 6 weeks. I'm not sure if I miscarried, or was never pregnant to begin with.