"Support team lead" or "support team leader"

Solution 1:

In my experience, a team lead is appointed (by a manager), and is assumed to be taking on some leadership responsibilities in addition to his normal duties as a team member...generally for no extra pay, I might add.

In another sense, a leader is someone who "steps up" and takes on challenges and/or inspires others, regardless of whether they have the official standing to do so. I have never heard the word lead used in this sense.

Otherwise, though, the phrases "team lead" and "team leader" are synonymous.

Solution 2:

The only use of ‘lead’ to describe a person that the OED records is the theatrical one: one who plays the principal part in a play. I have not seen it used as a synonym for ‘leader’. ‘Support the team lead’ surely means something subtly different from ‘support the team leader’. It highlights the position and its role rather than the person occupying it.