The Shocking Talent List ranks students based on their overall strength, determined through sparring and duels, while the Flying Spirit List ranks students according to their Spiritual Power. Though both seem to be based on strength, in reality, they are two completely different lists.
For one, engagements are one-on-one bouts, and it's not necessarily the case that those with strong Spiritual Power are suited for head-on confrontations. Moreover, overall strength includes elements such as strategy and tactics, and a strong Spiritual Energy doesn't guarantee intelligence, let alone combat power.
Moreover, comparatively speaking, the Shocking Talent List is fairer than the Flying Spirit List. This is because Spiritual Power is often related to one's background. Take Xi Ye for instance; as the son of the Demon Realm Emperor, his innate Spiritual Power is naturally unmatched.