Fuji Pentax Comparison

I have acquired a 55-300mm zoom lens for my Pentax and want to see if it will capture better images than my Fuji HS10. The photo shows two test shots taken today with them overlaid to show the difference in size of the images on the sensor. The smaller of the two is from the Pentax at 450mm equivalent, the larger from the Fuji at 720mm equivalent. The Fuji has only a tiny compact sized sensor of 10mp, the Pentax has an APS C sensor of 16mp. More mp, bigger sensor. Theoretically the larger image should reveal more detail, but the higher quality sensor on the Pentax should allow me to crop in to a similar size and get at least as good if not more detail. Sorry if I'm rambling!
Anyway the tests were inconclusive as the seeing was hazy and the Sun is bereft of spots at the moment!