The Emma/Xavier telepathic relationship.

Alright we know that since his creation Xavier has been the most powerful telepath on the planet. Barring telepaths such as Jean and Legion. Emma has always been sidelined when it came to grabbing that title simply because...well that's just it "because it's Xavier". Feats for Xavier have been given and for the most part Emma has matched those feats. So why is she not considered to be his equal? No one is saying that Emma would win against Xavier if they went in an all out battle. But you must admit that Emma has shown to be just as powerful as Xavier if not more so.

So my question is.. What makes Xavier so much more powerful than Emma that she'll never be his equal?