As initialisms the difference between tia and tic

is that tia is telecommunications Industry Association while TIC is tourist Information Centre.

As a proper noun Tia

is {{given name|female}} invented in the latter half of the twentieth century. It can be explained as a short form of Letitia or Venetia, or from Estonian Tiia, pet form of Dorothea.

As a noun tic is

a local and habitual convulsive motion of certain muscles.

As a verb tic is

to exhibit a tic; to undergo convulsive muscle movements.