Tebow, a junior, and Bradford, a redshirt sophomore, face a Thursday deadline for nonseniors to declare for the N.F.L. draft. And while each is a Heisman Trophy winner and a homegrown star at his state’s university, they project much differently as N.F.L. prospects. Both have filed paperwork with the N.F.L. to see where they are likely to be picked in April’s draft. Two rabid fan bases will be waiting anxiously for their decisions.