Technical Support generally is based on levels (I, II, III, etc.) and as the levels go up, the complexity of the calls increase and the volume decreases. Higher complexity requires a deeper knowledge of the product and an ability to work in-depth and 1:1 with the customer.

The ability to dive deeper also requires stronger abilities to document customer issues, work from your own knowledge (VS scripts for front-line support people), and potentially interface with the company design, product and development organization.

More senior support role duties may also include training of new specialists. The desire to be a trainer (formal in classroom or informal 1:1) should interest you if you say a "I want to be a level IV rep."