Don't understand why I'm seeing different secondary wave forms.

I have an OWON 1022I oscrope and have been trying to read my primary and secondary ignition wave forms. Today I got two different secondary wave forms on my CH2 that was connected to my #1 spark plug wire. If you look at the first picture, CH1 is back probed into the ground wire on the coil. The second picture, CH1 is clamped onto the coil wire. I understand what I was seeing on CH1 but not why the wave form is so different depending on which signal source CH1 is connected to. I'm thinking it is something to do with my scope but the S10 I have this connected to has a light load misfire issue I have been chasing. So can someone explain the reason for the difference. Channel #2 is the yellow one on the bottom.